Look for a tiny/small form factor Dell optiplex on eBay, used, open box or if price is low a new one. You need not buy the latest generation, but some decent i5, i7 8-10th gen or Ryzen gen 2

and 3 would do depending on your use case. You can add RAM later on most of these

MiniPC’s, except some very small form factors ones that come with soldered RAM.