itch.io

not the best option, but look for full sized computers coming out of large office buildings and the like (usually 150 to 250 bucks), they work fine but are a little slow. This is where getting a full sized and not a smaller one comes in, over time you upgrade the internals to have a  better pc as needed, and as can be afforded. aim for a 1080 or 1440p rig for now, you can always upgrade later since a lot of parts can change between mobos. also check amazon and other websites for CPU/MOBO combos and maybe a decent gpu and you can get a really nice running rig for around 600 bucks, and room for improvement