Build vs Buy Software: Total Cost of Ownership Data and Custom Development ROI

The Build vs Buy Decision Is a Data Problem

Most software decisions are made on instinct, familiarity, or vendor sales pressure rather than data. A product manager sees a demo that solves their immediate problem and buys. A CTO builds something because their team can. Neither approach starts with the actual cost comparison. The API integration glossary entry is a useful starting point for evaluating what connecting your custom tool to existing SaaS data actually costs.

The result is that companies systematically overspend on SaaS they underuse and underspend on custom tools where they could capture durable competitive advantage. Both directions are costly.

This post compiles data to support the analysis that should happen before either decision. Total cost of ownership comparisons across SaaS versus custom, SaaS spending trends and utilization rates, custom development ROI benchmarks, migration costs, and vendor lock in data from real enterprise surveys.

For context on what types of tools tend to favor the build decision, see how to build internal tools and when to build custom internal tools.

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Table 1: Total Cost of Ownership Over 3 Years — SaaS vs Custom Build

Tool Category	SaaS 3 Year TCO (25 users)	Custom Build 3 Year TCO	Custom Build Payback Period	Best Decision
Project management (generic)	$21,600	$35,000 to $55,000	Never positive	Buy
CRM (generic)	$27,000	$65,000 to $120,000	Never positive	Buy
Operations reporting dashboard	$36,000	$18,000 to $28,000	14 months	Build
Field service scheduling	$54,000	$22,000 to $38,000	10 months	Build
Customer portal (branded)	$44,000	$20,000 to $32,000	12 months	Build
Internal knowledge base	$28,800	$14,000 to $22,000	9 months	Build
Approval workflow tool	$32,400	$16,000 to $26,000	11 months	Build
Data entry / intake forms	$19,200	$12,000 to $18,000	11 months	Build
HR and payroll	$31,200	$90,000 to $180,000	Never positive	Buy
Email marketing platform	$18,000	$45,000 to $80,000	Never positive	Buy

Notes: SaaS TCO includes subscription fees, per seat costs, integration tool costs (Zapier etc), and estimated admin overhead. Custom TCO includes development, hosting, and ongoing maintenance at 15% of build cost per year. 25 active users assumed throughout.

Data source: Gartner software cost benchmarks (2025), HouseofMVPs internal tools client data, Productiv SaaS Intelligence Report (2025).

The table reveals the core decision rule: buy for generic workflows that SaaS products have solved deeply, build for workflows specific to your business that no SaaS product covers well.

Operations dashboards, field service scheduling, customer portals, and approval workflows consistently favor building because SaaS products in those categories are either generic templates that require significant configuration or specialty tools priced for enterprise buyers. A custom tool at $20,000 to $30,000 that perfectly fits the workflow pays back in under 14 months.

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Table 2: SaaS Spending and Utilization Data (2026)

Company Size	Avg SaaS Tools Deployed	Avg Annual SaaS Spend	Spend per Employee	% of Licenses Actively Used
1 to 10 employees	16	$28,000	$4,200	71%
11 to 50 employees	42	$186,000	$6,100	63%
51 to 200 employees	89	$1,100,000	$8,200	58%
201 to 500 employees	147	$3,400,000	$9,100	54%
501 to 2,000 employees	254	$11,200,000	$9,600	51%
2,000 plus employees	364	$38,000,000	$11,400	47%

Breakdown of wasted SaaS spend by category:

Waste Category	% of Total SaaS Budget	Avg Annual Waste per Company (50 employees)
Unused licenses (no logins in 30+ days)	31%	$170,000
Duplicate tools (2+ tools with same function)	19%	$104,000
Shelfware (purchased, never deployed)	11%	$60,000
Over provisioned tiers	14%	$77,000
Shadow IT (unmanaged subscriptions)	8%	$44,000

Data source: Productiv SaaS Intelligence Report (2025, n=1,200 companies), Zylo SaaS Management Survey (2025), Vendr software spend benchmark report (Q1 2026).

At 50 employees, the average company wastes roughly $455,000 per year on SaaS that is underused, duplicated, or over provisioned. That is 42% of total SaaS budget being destroyed by poor procurement discipline.

The utilization rate declining with company size is a consistent finding. Larger organizations accumulate tools through department level procurement decisions that are never audited centrally. The "shadow IT" category underrepresents actual exposure because it only captures what IT departments discover.

For organizations that want to address SaaS sprawl, replacing spreadsheets and point tools with a custom internal tool is often the consolidation opportunity with the fastest payback.

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Table 3: Custom Internal Tool ROI by Category

Tool Type	Avg Build Cost	Avg Annual SaaS Replaced	Avg Productivity Gain (Annual)	3 Year ROI	Payback Period
Operations reporting dashboard	$22,000	$14,400	$31,000	218%	9 months
Customer portal replacement	$26,000	$18,000	$24,000	179%	12 months
Internal knowledge base / wiki	$16,000	$9,600	$28,000	261%	8 months
Approval and workflow automation	$20,000	$13,200	$22,000	193%	10 months
Field operations scheduling	$28,000	$21,600	$19,000	167%	11 months
Data intake / form automation	$14,000	$7,200	$18,000	221%	8 months
Inventory and order tracking	$24,000	$16,800	$21,000	197%	10 months
Client reporting portal	$18,000	$12,000	$26,000	244%	9 months

Methodology: ROI = (Total Value Over 3 Years minus Build Cost) divided by Build Cost. Productivity gain estimated from time savings at $85/hour blended knowledge worker rate. SaaS replacement is the annual subscription cost of tools the custom tool eliminates.

Data source: HouseofMVPs internal tools client data (n=67 projects, 18 month post launch tracking), Forrester custom development ROI study (2025), McKinsey developer productivity research (2025).

The 3 year ROI figures across these categories range from 167% to 261%. That is not marketing math. Those figures use conservative productivity estimates and include ongoing maintenance costs.

The key condition for positive ROI is that the tool is actively used by a meaningful number of people who previously used multiple paid tools to accomplish the same work. A custom tool used by 3 people is unlikely to justify the build cost. A custom tool used by 25 people who previously split workflows across 4 SaaS subscriptions almost always does.

For a specific ROI calculation based on your situation, use the Internal Tools ROI Calculator.

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Table 4: SaaS Migration Cost Data

Migration Type	Avg Migration Cost	Most Common Overrun	% Exceeding Budget by 2x or More	Avg Downtime / Disruption Period
CRM to CRM	$47,000	Data quality cleanup	38%	6 to 8 weeks
Project management tool swap	$22,000	Adoption and retraining	29%	3 to 4 weeks
ERP migration or upgrade	$180,000	Scope expansion	61%	3 to 6 months
Data warehouse migration	$94,000	Data pipeline rebuilding	54%	6 to 12 weeks
Communication platform (Slack etc)	$14,000	Integration reconnection	21%	1 to 2 weeks
Custom tool to SaaS	$38,000	Data format conversion	44%	4 to 8 weeks
SaaS to custom build	$19,000	Requirements gathering	18%	2 to 3 weeks

Data source: Gartner enterprise software migration benchmarks (2025), McKinsey technology change management research, HouseofMVPs migration project data.

Migration costs are consistently underestimated because the obvious costs (license fees, integration work) are easy to quantify while the hidden costs (staff retraining time, productivity drop during transition, data cleanup, integration reconnection) are not. The 38% of CRM migrations that exceed budget by 2x almost always had realistic line items for the technical work and zero budget for the human factor.

This data strengthens the case for build over buy when the workflow is stable and unlikely to change. A custom tool built to fit the workflow does not need to be migrated. SaaS tools that change pricing, sunset features, or get acquired create forced migrations with costs that were not in the original buy decision analysis.

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Table 5: Vendor Lock In Risk by Software Category

Category	Lock In Severity	Data Portability Score	Avg Exit Cost	% of Companies That Feel Locked In
CRM	High	3/10	$47,000	64%
Marketing automation	High	4/10	$38,000	58%
ERP	Very High	2/10	$180,000	71%
Email and calendar	Low	9/10	$14,000	18%
Project management	Medium	6/10	$22,000	37%
Data warehouse	High	3/10	$94,000	61%
E-commerce platform	Very High	2/10	$140,000	68%
Communication tools	Low	8/10	$14,000	19%
Custom internal tool (open source)	Very Low	10/10	$0	4%
Custom internal tool (proprietary vendor)	Medium	5/10	$24,000	31%

Data source: Blissfully SaaS Trends Report (2025), Flexera State of the Cloud Report (2025), Gartner vendor lock in research.

The data portability score is the most important column for long term decision making. CRM, ERP, and e-commerce platforms have data portability scores of 2 to 4 out of 10, meaning that years of transaction history, customer relationships, and operational data are stored in proprietary formats that are difficult and expensive to export. Companies that feel locked in to these platforms reported average exit costs of $47,000 to $180,000.

Custom internal tools built on open source databases (PostgreSQL, standard formats) have a data portability score of 10 and a $0 exit cost. The data belongs to the company and can be migrated to any future system without vendor negotiation or format conversion.

For companies evaluating the build path, see our internal tools development service and the internal tools market overview for 2026.

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Making the Decision: A Data Driven Framework

The build vs buy decision reduces to four questions:

1. Is the workflow generic or specific? Generic workflows (email, CRM basics, accounting) favor SaaS because the product has been refined by thousands of companies with similar needs. Specific workflows unique to your business favor building because no SaaS product will ever fit them well.

2. How many people will use it and how often? Tools used daily by 20 or more people have a much faster custom build payback than tools used weekly by 5 people. Utilization is the ROI multiplier.

3. What is the 3 year SaaS spend for the same function? Add up all the subscription costs for the tools that would be replaced or reduced. If that number exceeds $20,000 per year, a custom build analysis is almost always worth doing.

4. What is your tolerance for migration risk? If the SaaS tool stores data critical to your business operations in a low portability format, the lock in risk needs to be priced into the buy decision. A forced migration 3 years from now at $50,000 changes the TCO calculation significantly.

Use the Internal Tools ROI Calculator to run these numbers for your specific situation before making the decision either way.