I bought an Optiplex 7050 SFF for $100 USD at the start of 2023. Upgraded it to an i7-7700, 32GB RAM, 300W PSU from an XE3 model (stock is 180W), and threw in a spare Nvidia K1200 Quadro for shits and giggles. Runs almost my entire suite of self-hosted applications without a hitch.