Search "build vs buy software" and notice who wrote the top results: SaaS companies. Their conclusion, reached with suspicious consistency, is buy, specifically, buy theirs.
Ask a development agency instead and the conclusion mysteriously reverses.
Everyone answering this question is selling one of the answers. So are we, technically, we build. Which is exactly why this article is going to do the math honestly in both directions, including the direction that costs us projects. (First, though: confirm you've passed the earlier gate of whether you need software at all, build-vs-buy is question two, and plenty of businesses are still on question one.)
The two lies that frame the debate
The buy-side lie is the pricing page. ₦15,000 a month sounds like nothing. But subscriptions are quoted in months and lived in years, and they scale with you: per user, per contact, per feature tier. The plan that costs little at 3 staff and 500 customers costs something very different at 15 staff and 20,000 customers, and by then your data, workflows, and habits live inside the tool. That's the trap part: not the price, the position, renting a system you can't leave, with a landlord who sets the rent.
The build-side lie is the quote. The build cost is the entry fee, not the price. Software needs hosting, maintenance, security updates, and evolution, the industry's own rough rule puts ongoing costs at a meaningful percentage of build cost, every year, forever. An agency quoting a build price with no mention of the years after is running the same trick as the pricing page: showing you the visible fraction of a total cost of ownership.
Honest comparison means both numbers over the same five years. Almost nobody runs it. It fits on a napkin:
Buy: subscription × realistic growth in users/tiers × 60 months, plus the exit cost of ever leaving. Build: build quote + (hosting + maintenance) × 5 years, a realistic view of what building actually costs, minus what the asset is worth if you sell, license, or keep scaling it at zero marginal cost.
Run it with your real numbers. The answer changes per business, which is the point, and the reason generic conclusions are all sales copy.
The four questions that actually decide it
1. Is this workflow your edge, or your plumbing? The clean dividing line. Accounting, email, payroll, plumbing; every business does it roughly the same way, and world-class tools exist for pennies on the custom-build naira. Buying plumbing is always right. But the workflow that makes customers choose you, your intake process, your delivery logistics, your matching engine, is your edge, and renting your edge means renting it from someone who'll happily lease the same edge to your competitor. Buy your plumbing. Own your edge. Most of the decision is done right there.
2. How weird are you? SaaS is built for the average business in a category. If you fit the average, buying is a gift, thousands of businesses funded a tool's refinement before you arrived. If you're structurally unusual (hybrid model, unusual market, workflow the tools keep fighting), you'll spend your subscription plus endless workaround labor. The tell: you're maintaining spreadsheets around your paid software to cover what it won't do. That's paying rent and doing the landlord's repairs.
3. What happens at 10x your current size? Subscriptions scale linearly with heads and usage; built software scales with a flatter curve, the build cost amortizes across every new user at nearly zero marginal cost. If you genuinely plan to be 10x bigger, the lines cross somewhere, and it's worth knowing roughly where before you're standing on the crossing point with all your data in the rented building.
4. Can you feed what you build? The disqualifying question, asked with love. Built software is a living thing, it needs updating, securing, evolving. If there's no budget or appetite for after-launch care, do not build, whatever the napkin says. An unmaintained custom app quietly becomes a security liability wearing your logo, and the subscription, where maintenance is the landlord's problem, was the right call all along.
The answer the debate format hides: both
Real businesses rarely land on one side cleanly, and the strongest pattern we see is the hybrid: buy every commodity, build the one thing. Accounting on SaaS, email on SaaS, payroll on SaaS, and one custom-built system for the single workflow that is the business, integrated with the rented plumbing around it.
This is how you get asset economics where they matter and rental convenience where they don't, and it's the answer neither side of the debate industry promotes, because it means selling you less.
The napkin, one more time
Your edge or your plumbing? How weird? What size at 10x? Can you feed it?
Four questions, five-year math, both directions. Answer them honestly and the build-vs-buy decision mostly makes itself, and whichever way it lands, you'll have made it as an owner doing arithmetic, not an audience for someone's pricing page.