I have 6 and ended up needing to use my gaming PC for a build server.

I think you could get by with 1 computer, but it’ll have to have a pretty decent machine.

Between agents running tests, CI, docker image builds, an average $400 mini PC won’t cut it.

Don’t forget also many older mini PCs don’t support KVM. Some newer ones don’t support AVX/ mongodb.

It’s not so easy to buy any old hardware sadly.

You might be right, it likely needs a full proper PC setup with the test suite stuff. I was looking at this vendor, https://www.gmktec.com/collections/all there's this whole AI mini-pc market but they aren't quite a full dev machine replacement

I’m running ~5 agents at a time very comfortably on a $280 mini PC with 8GB. They’re all in Docker containers, a couple have sidecar VMs they can own and run. Not having any issue with load.