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 for your services, and a big case with spare parts and lots of drives for your NAS. Especially at the price you mentioned. Just remember you can separate your services easily, so don't focus on getting everything in one spot, you can make your requirements (and cost) go up quickly.