Maybe this provides a good starter read: https://www.servethehome.com/introducing-project-tinyminimicro-home-lab-revolution/
There are more in detail later articles, also dealing withore modern units, and the prices are from 2020, where lockdown and other factors spiked a big demand.
I’m more into beginner’s server units, and I’ve sourced a Supermicro X10 based 1u server for EUR 75 including shipping on one ebay night.
Patience is the key, and probably best set yourself an upper limit price wise.
poVoq@slrpnk.net 1 year ago
Search for “refurbished thin client” or something like that. The popular ones are usually from HP.