For lots of services that require little CPU and ram, I use tiny/mini/micro PCs, bought used. I get them for anywhere from $100-$400, and usually all I do is drop in an SSD. That includes Linux VMs when I’m testing distros or deployment on a distro, since 32gb ram on the host is more than enough to leave 4-8gb ram to the VM.

For some heavier applications, I also have a 4RU case stacked with drives, which I use as a third NAS (VM with drives passed through), large DBs, etc. Its just a 1700x with 64GB ram, and that’s plenty.

For most things (DNS, a few web servers, git, grafana, Prometheus, rev proxies, Jenkins, personal fdroid repo, homepage, etc) I just use the tiny/mini/micro’s. Imo, you can’t go wrong with those.