In 2019, a mid-market logistics company chose to build their own order management system. The decision made perfect sense at the time: their workflows were unique, off-the-shelf solutions didn’t fit, and they had a strong engineering team.

Five years later, that system is their biggest liability. The architect who designed it left. The custom integrations are fragile. Every new feature takes 3x longer than expected. And the commercial solutions that “didn’t fit” in 2019 have evolved to support their exact use case.

This is the build vs. buy trap: the decision was correct at the time it was made. But the world changed, and the decision wasn’t revisited.

The Decision Decay Problem

Build vs. buy is not a one-time decision. It’s a continuous evaluation that most organizations treat as permanent.

The factors that influence the decision change constantly:

• Your business changes. The “unique workflows” that justified the custom build may become standardized as you scale.
• The market changes. Vendors add features. New competitors emerge. Pricing models evolve.
• Your team changes. The engineers who built the system leave. Institutional knowledge walks out the door.
• Technology changes. The framework you chose becomes outdated. Integration standards evolve.

A build decision made with perfect information in 2020 may be catastrophically wrong by 2026. Yet most organizations never perform a second evaluation.

The True Cost of Building

Organizations chronically underestimate the total cost of ownership for custom software. Here’s what the initial estimate always misses:

Ongoing maintenance. Custom software doesn’t maintain itself. Budget 20-30% of the original build cost annually for bug fixes, security patches, dependency updates, and infrastructure maintenance.

Opportunity cost. Every engineer maintaining your custom CRM is an engineer NOT building product features that generate revenue. For a team of 3 maintaining an internal tool, that’s $500K-$800K/year in opportunity cost.

Knowledge concentration risk. When the engineer who built the system leaves — and they will leave — you face a choice between hiring an expensive replacement or reverse-engineering the system from scratch.

Integration burden. Custom systems don’t come with pre-built integrations. Every new tool your company adopts requires custom integration work.

The True Cost of Buying

But buying isn’t free either. Organizations also underestimate the long-term costs of commercial software:

Vendor lock-in. Once your data lives in a vendor’s platform and your processes are built around their workflows, switching costs become prohibitive. Vendors know this, which is why Year 1 pricing is always the best pricing.

Configuration debt. Complex enterprise software accumulates configuration debt — custom fields, workflows, integrations, and automations that become increasingly difficult to maintain or understand.

Upgrade cycles. Vendors deprecate features, change APIs, and mandate version upgrades. Each upgrade cycle requires testing, retraining, and sometimes configuration rework.

The Decision Framework

Instead of asking “should we build or buy?” — which implies a binary, permanent choice — ask these questions annually:

1. Is this a differentiator?

If the software gives you a competitive advantage, build it. If it’s infrastructure that every company needs, buy it.

No company has ever won a customer because their internal HR system was custom-built. Many companies have won customers because their product technology was superior.

2. What’s the switching cost?

Calculate the cost of switching from your current approach (build or buy) to the alternative. If switching is cheap, the decision is low-stakes. If switching is expensive, the decision needs more diligence.

3. Where is the vendor headed?

Study the vendor’s roadmap. Are they building toward your needs or away from them? A vendor pivoting to a different market segment will deprioritize your use case, even if they currently serve it well.

4. Where is your team headed?

If you’re planning to double your engineering team, the economics of building improve. If you’re planning to stay lean, the economics of buying improve.

The Annual Audit

Add this to your annual technology review:

For every custom-built system:

• What is the annual maintenance cost? (Include opportunity cost)
• Could a commercial solution now handle this use case?
• What’s the risk if the primary maintainer leaves?

For every purchased system:

• What’s the annual total cost (license + administration + integration)?
• Is the vendor’s roadmap still aligned with our needs?
• What’s the switching cost if we needed to change?

The organizations that make the best technology decisions are the ones that treat build vs. buy as a living evaluation, not a historical artifact.

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The Garnet Grid perspective: We help organizations evaluate their technology portfolio with clear financial modeling and strategic analysis. Because the most expensive software decision is the one you made five years ago and never questioned. Explore our advisory services →