Build vs. Buy: Total Cost of Ownership Analysis
The build vs. buy decision extends far beyond upfront costs. A custom-built solution has high initial investment but predictable ongoing costs; a commercial SaaS solution has lower entry costs but annual fees that compound significantly over time. The crossover point — where building becomes cheaper — is the critical decision variable.
A 2024 Gartner survey found that 63% of enterprises underestimate the long-term cost of building custom software by 40–80%, primarily due to underestimating ongoing maintenance, security patching, and feature development. Build decisions should include a 3–5 year TCO model, not just year-one costs.
Cost Component Comparison
| Cost Element | Build (Custom) | Buy (Commercial) |
|---|---|---|
| Development | High (100%) | Low (implementation only) |
| Annual maintenance | 15–25% of build cost | Included in license |
| Customisation | Unlimited | Limited by vendor |
| Security patches | Your responsibility | Vendor's responsibility |
| New features | Your roadmap | Vendor's roadmap |
| Vendor lock-in risk | None | High |
TCO Formula
Beyond Cost: Strategic Factors
Build advantages: Full IP ownership, exact feature fit, competitive differentiation, no vendor dependency.
Buy advantages: Faster deployment (weeks vs. months/years), established support, regular updates, shared R&D costs across thousands of customers.
- Engineer salaries and benefits (typically 60–70% of total build cost)
- Project management overhead (10–15%)
- QA, security review, and compliance (10–20%)
- Documentation and training (5–10%)
- Ongoing tech debt accumulation