I've bought old thinkpad T-series on ebay for ~$300, installed arch, and moved on with my life. I keep most of my relevant data on git repos or a home server. If it dies, which usually happens after a good few years, I just get a new one. Not ideal, and certainly not for everybody, but a reasonable option if it fits your needs.
That's actually a good idea if you don't need too much extra horsepower. You get a good keyboard, an acceptable display, and a lightweight machine for a don't-care-if-you-drop-it price.
