Why AI Changed the Build vs. Buy Decision

Sooner or later, every development leader gets this question.

Someone on your leadership team sees a vendor demo. Every shiny feature they've been asking for is already built in. They come back from the meeting and ask: "Why are we still building things ourselves? Why don't we just buy it?"

It's a fair question. And for a long time, the answer was often "you're right, we should buy it." Building custom software was slow and expensive, and buying got you there faster.

But most of the build vs. buy analyses companies are relying on were done before AI-assisted development changed the math. If your analysis is older than your team's AI tooling, it's probably out of date.

Here's how I'd think about it now.

What doesn't show up on the vendor invoice?

When you compare a vendor quote to the cost of building, the vendor almost always looks cheaper. That's because the quote only shows you the first part of the story.

And that cycle doesn't happen once. Every time you switch vendors, the switching tax comes due again. A competitor's lower price can look like savings on paper, but the hidden transition costs come right back around.

What can't you see inside a vendor's product?

This matters even more when the product you're buying includes AI features.

In a recent article, I laid out five questions to put every AI feature through before you build it: Value, Fit, Risk, Operability, and Trust. Try running those same five questions on a vendor's product, side by side with what you'd build yourself.

Vendor products are often a bit of a black box. You don't get the same visibility, and you don't get the same control. Sometimes that's an acceptable trade. But it should be a trade you make on purpose.

Why did the math change?

Two years ago, a lot of build options lost to buy on time and cost alone. That's shifting.

AI-assisted development tools have moved the build curve. In my own recent projects, work that used to take weeks now takes days, and the maintenance work that used to eat up capacity goes faster too. That changes both sides of a build vs. buy comparison: the cost to build it, and the cost to keep it running.

But don't just take my word for it, because your number is the one that matters. Measure your own team. Track how long work takes with and without AI-assisted tools for a few months, then rerun your build vs. buy analysis with real data instead of assumptions.

And there's one more advantage on the build side that doesn't show up in a spreadsheet: a system you build is one you never have to re-procure, migrate away from, or lose institutional knowledge over.

So who actually builds it?

Here's where a lot of build plans fall apart. Deciding to build is one thing. Having the capacity to build, and to build it well, is another.

You really have three options.

That third option is the one most companies don't realize they have. You don't have to choose between building your own engineering department from scratch and handing work to a vendor you can't see into.

But there's one thing to watch for. A contract team can create its own switching tax if people keep rotating in and out. The answer is continuity: a team that learns your platform and stays with it, with documentation and leadership that keep the knowledge where it belongs. That's how we run dedicated development teams at PALADEM.

When does buying still win?

To be fair, building isn't always the answer. Buying usually still makes sense when:

• It's a commodity. Email, payroll, accounting, and the like. Nobody wins customers with a custom-built payroll system.
• It isn't a competitive advantage. If the software doesn't make you different from your competitors, there's less reason to own it.
• The vendor carries a burden you don't want. Some products come with certifications, compliance work, or infrastructure that would be expensive to replicate.
• You have no plan to own it. If nobody will steward the system after it launches, a vendor might be the safer bet.

The point isn't that you should always build. It's that the comparison deserves fresh numbers.

What keeps the build path defensible?

When stakeholders push back on building, there's usually a real worry underneath: "Are we just going to end up with another legacy system nobody wants to touch?"

It's a fair concern. And here's the honest answer.

What makes the build path viable is the discipline around it: the five questions for every AI feature, a clear decision policy for what ships, monitoring after launch, and regular reviews to keep it honest over time. That isn't overhead on the build path. It's what makes the build path work.

That's what software stewardship is about. You're not just building something. You're committing to look after it for as long as it serves the business, which is the whole idea behind our Software Stewardship Framework.

Bring your own numbers

The next time someone asks "why don't we just buy it?", don't answer with a gut feeling. Answer with:

1. The full cost of the vendor option, including renewals and the switching tax, not just the first-year quote.
2. The five questions, run side by side on the vendor's product and on what you'd build.
3. Your own team's real delivery speed with today's tools.
4. A plan for who builds it, who leads it, and who stewards it after launch.

Sometimes buying will still win. But if your analysis is more than a couple of years old, you might be surprised how often building comes out ahead now.