You can get MFF Dell/HP/Lenovo refurbs from Microcenter (and elsewhere) for 200-300 USD. Typically 9th or 10th gen i5 processors and 16 or 32 GB of RAM. You can fit them into 10 inch racks you can 3d-print (often with matching 3d printed brackets for a proper fit). We've been using them to replace some of our utility servers that we pay way too much for in the cloud (obviously that's a trade off of dollars for being concerned with security/management). We're treating them like cattle, deploying via K3S.