Build versus buy, and the cost the invoice hides.
Off-the-shelf software always looks cheaper at the point of sale. The question is what it costs once your team has to work around it.
The build-versus-buy decision is usually framed as a price comparison. A SaaS subscription has a number on it. A custom build has a larger one. On that basis, buying wins almost every time, and for most needs it should.
The cost the invoice hides
What the subscription price leaves out is the cost of fit. Every time a tool does not match how your team works, someone pays the difference: in manual steps, in data rekeyed between systems, in reports assembled by hand, in the workarounds that harden into tribal knowledge. None of it appears on an invoice, so it rarely enters the decision. It is real all the same, and it compounds as you grow.
When buying is right
Buy when the problem is common and your way of solving it is not a differentiator. Email, accounting, payroll, document storage: these are solved, and a custom version would be effort spent matching what you can license cheaply. If a standard tool fits most of the work and the rest is tolerable, buy it and move on.
When building is right
Build when the process is the business, when no tool fits without bending your operation around it, or when per-seat licensing taxes the very growth you are paying for. The signal is rarely a missing feature. It is the slow accumulation of workarounds, the spreadsheet that shadows the official system, the hour someone spends every morning moving numbers between tabs.
The honest comparison
Compare the total cost of fit, not the sticker price. Add the operational cost of the workarounds to the subscription, project both forward as you scale, and set that next to the cost of building the thing once and owning it. Sometimes buying still wins. When it does not, the gap is usually much wider than the invoices suggested.
Most operations run a mix: licensed tools for the commodity work, custom software for the few things that are genuinely theirs. The skill is knowing which is which.