The Build vs Buy Decision Is Costing You More Than You Think
Every growing company faces the build vs buy dilemma. Most get it wrong - not because they pick the wrong option, but because they evaluate it with the wrong framework. Here's how to stop bleeding money on the wrong side of the trade-off.
At some point, every company that relies on software hits the same fork in the road. Do we buy a tool off the shelf, or do we build our own? The decision feels straightforward. It almost never is.
We’ve watched companies spend six figures building internal tools they could have replaced with a $200/month SaaS subscription. We’ve also watched companies duct-tape together seven different platforms, paying $40k/month in subscription fees, when a single custom system would have cost less to build and maintain.
Both paths were wrong. And in both cases, the mistake wasn’t the technology. It was the framework they used to decide.
Why the standard analysis fails
The typical build vs buy evaluation looks something like this: list the features you need, compare them to what’s available on the market, estimate the cost of building it yourself, and pick the cheaper option.
This misses almost everything that matters.
The real costs of buying aren’t in the subscription fee. They’re in the workarounds. Every SaaS product makes assumptions about your workflow. When those assumptions don’t match, you start building around the tool instead of with it. Zapier glue. Export-import rituals. Manual steps that “only take five minutes” but happen forty times a day. A year later, your team is spending more time managing tool limitations than doing actual work.
The real costs of building aren’t in the initial development. They’re in the maintenance. That internal tool your team built in three months? It needs updates when dependencies change. It needs fixes when edge cases surface. It needs documentation so the next person can understand it. It needs someone who cares about it. And that someone is usually your most expensive engineer, doing work that has nothing to do with your core product.
The sticker price - whether it’s a SaaS invoice or a developer’s time estimate - is almost never the actual cost. The actual cost includes everything that happens after the decision.
The three questions that actually matter
Forget feature matrices. When you’re deciding between build and buy, there are really only three questions worth asking.
1. Is this your core differentiator?
If the thing you’re building is central to what makes your product or business unique, build it. Full stop. Don’t outsource your competitive advantage to a vendor who sells the same tool to your competitors.
If it’s not your differentiator - if it’s accounting, HR, email marketing, project management, CRM - buy it. You are not going to build a better CRM than Salesforce. You are definitely not going to maintain one.
This sounds obvious, but companies mess it up constantly. They build custom analytics dashboards when Metabase exists. They build custom CRMs when they have twelve customers. They build custom scheduling tools because “our workflow is unique.” Your workflow is not that unique. It just feels that way from the inside.
2. How much will you need to bend the tool?
Every SaaS product has a “happy path” - the workflow it was designed for. If your needs align with that path, buying is almost always right. The tool will be better maintained, better documented, and more reliable than anything you’d build.
But if you’re going to spend months configuring, customising, and building integrations to make an off-the-shelf product fit your process, you’ve already lost the advantage of buying. You’re paying the subscription fee AND doing the engineering work. Worst of both worlds.
The threshold is roughly this: if you need to customise more than 30% of the tool’s functionality to make it work, you should probably build. Below that, buy and adapt your process to the tool. Yes, adapt your process. The tool has opinions for a reason, and those opinions are usually based on patterns from thousands of other companies.
3. What’s the switching cost in two years?
This is the question nobody asks, and it’s often the most important one.
When you buy a SaaS product, your data lives in someone else’s system. Your workflows depend on their API. Your team builds muscle memory around their interface. Two years from now, if that vendor raises prices by 300% (it happens), gets acquired and sunsets features (it happens more), or simply shuts down (it definitely happens) - what’s your exit plan?
If the switching cost is low - your data exports cleanly, alternatives exist, and migration is a weekend project - buying is low risk. If your entire operation would grind to a halt, you’ve handed a vendor leverage they will eventually use.
Building gives you control. That control has a cost in engineering hours. But it also means nobody can pull the rug out from under you.
The hybrid approach that actually works
The smartest companies we work with don’t treat this as a binary choice. They buy for everything that isn’t core, build for everything that is, and design the connection layer between them.
That connection layer is the key. Instead of letting SaaS tools become load-bearing walls in your architecture, treat them as replaceable modules. Use APIs. Keep your data in your own systems and sync it outward. Build thin integration layers that you control, so swapping one vendor for another is a configuration change, not a rewrite.
This takes more upfront thought than just signing up for a tool and dumping data into it. But it means you’re never locked in, and you’re never starting from zero.
The real trap: deciding once and never revisiting
The worst version of the build vs buy mistake isn’t picking the wrong option. It’s picking an option and treating it as permanent.
That SaaS tool you bought three years ago when you had five employees? It might be costing you $3,000/month now with 50 seats, and you’re only using 20% of its features. That custom tool you built two years ago? The engineer who wrote it left, nobody’s touched it since, and it’s now a liability.
Build vs buy isn’t a one-time decision. It’s a recurring evaluation. What made sense at one scale stops making sense at another. The companies that manage this well revisit their tooling every 6-12 months and ask: is this still the right side of the trade-off?
The bottom line
Stop thinking about build vs buy as a cost comparison. Think about it as a leverage question. Where does owning the software give you leverage? Where does renting it free you up to focus on what matters?
Build the things that make you different. Buy the things that make you functional. Design the connections so you can change your mind. And revisit the decision before it revisits you.
The companies that get this right don’t necessarily spend less on software. They spend it in the right places. And that difference compounds every single quarter.