Build by Lunch
How the plummeting cost of code is reshaping the boundaries of the modern firm.
In 1931, a twenty-one-year-old Englishman named Ronald Coase spent a year wandering the factory floors of American industry on a traveling scholarship, notebook in hand, watching Ford and General Motors decide what to make and what to buy. He kept circling one question his economics professors couldn’t answer. If markets are so efficient, if the price system coordinates everything, why does a company like Ford employ thousands of people inside its own walls instead of contracting each task out to the open market every morning? Why is there a firm at all?
The received answer, then and now, was that companies buy whatever is cheaper to buy and build whatever is cheaper to build. Obvious. A carmaker doesn’t smelt its own steel if the mill down the road does it for less; it doesn’t write its own accounting package if a vendor sells one off the shelf. The edge of the company falls wherever the math falls. Buy the cheap thing, make the dear one, and let the prices sort it out.
But there is a problem with that theory. It turns out the prices don’t sort it out, because using the market isn’t free. Coase published the answer in 1937, in a paper called “The Nature of the Firm,“ and it won him a Nobel more than half a century later. Every time you buy instead of build, he saw, you pay a second, hidden bill on top of the sticker price: the cost of finding the supplier, negotiating the contract, policing the terms, waiting for delivery, and living with whatever you’re handed. He called these transaction costs. A firm exists, Coase argued, precisely to swallow the work whose transaction costs run higher than the cost of just doing it in-house. The company’s edges are drawn along that waterline, where the cost of buying finally rises above the cost of making.
Forty years on the buy side
For software, that waterline has sat in almost the same place for forty years, and it has always favored buying. Building was the expensive side. To make your own platform you needed a team of engineers, a year of calendar, a budget with six figures in it, and the patience to maintain the thing forever after. Buying meant a license and a login. So companies bought. They bought the ERP, the IoT platform, the analytics suite, and they accepted the tax that came folded inside: the feature you needed but didn’t get, the workflow bent to fit the vendor’s assumptions, the forum post requesting a change, the upvotes, the roadmap webinar, the year of waiting, the slow recognition that the feature would never ship at all.
Today the building side of that waterline is collapsing. In a recent video, Walker Reynolds, who consults for manufacturers on industrial software, explains how he built two full platforms over the past year using coding agents, and he puts the arithmetic plainly: about four thousand dollars a month in usage, roughly fifty thousand dollars to develop tools that would have cost a fortune five years ago. That isn’t the headline, though. The headline is what fifty thousand dollars now buys in time. “I could come up on a Monday morning,” he says, “with a feature that I need in my platform that I can develop by lunch. The commercial OEM can’t develop that solution for you that fast.”
Read that against Coase and you can watch the waterline move. The license fee was never the real cost of buying. The real cost was the wait, the petition, the powerlessness: the distance between needing a thing on Monday and maybe getting it a year from now. That distance was a transaction cost, and it was enormous, and we paid it without ever putting a number on it because the alternative, building it ourselves, was unthinkable. Now the alternative thinks itself into existence by lunch.
The bills come due on buying
When the cost of building falls toward zero, every one of those hidden bills comes due on the buy side instead. You feel the drag of the vendor’s roadmap because you no longer have to suffer it. You notice you’re paying for nine features to get the three you use. You watch your own feature request gather dust in a forum while, in another tab, an agent ships the same thing into your own toolkit before you finish your coffee. The math that always pointed toward buying starts, item by item, to point the other way.
A jagged boundary
This is not a prophecy that everyone becomes a software company and the vendors all die. Reynolds is careful here, and he’s right to be. The world he describes is stranger and more mixed than that. You’ll still buy the commercial platform; some things genuinely are worth buying, the deep and dull and costly infrastructure nobody wants to own. But you’ll stop letting it dictate the edges of what you can do. You’ll build the small tools tuned exactly to your shop floor and your data, and bolt them onto the commercial software you chose not to build yourself. The firm’s boundary doesn’t vanish. It gets jagged. It runs through the middle of your software stack now, bought parts and built parts interlocking along a seam that you, not the vendor, get to draw.
The skill that decides where that seam falls is no longer the ability to write code. Generation got cheap; an agent will produce a working dashboard for anyone who asks. What stays scarce is the judgment to know which feature is worth a Monday morning and which is worth a purchase order, which problem your team should swallow and which it should rent. Coase handed us the question in 1937, and it’s the same question now, only the answer changes weekly: where does it cost you less to make than to buy? For two generations the software answer was fixed, and we built whole industries on the assumption that it would stay fixed.
Reynolds doesn’t pretend to like it. “I don’t know if I necessarily even like that that’s the reality,” he says, and then: “we must operate in the real world.” That’s the honest posture. The waterline isn’t moving because anyone voted for it or because a vendor announced it from a stage in Orlando. It’s moving because the cost of building dropped, and costs, once they drop, don’t ask permission before they redraw the map.
Coase spent a year on factory floors to find the line that separates what a company makes from what it buys. He found that the line is alive, that it breathes in and out with the cost of coordination. He just never got to watch it move this fast. The line still runs through every business that touches software. For the first time in forty years it’s drifting toward you, and the question was never whether to defend the old position. It’s which side of the new line each thing belongs on.