Refurbished chromebooks for $43-$50:
https://computers.woot.com/plus/chromebooks-extravaganzaI've bought some chromebooks on Black Friday sales for $75 and they're AMAZING for kids in middle or high school who have to write papers and things when the main 'family computer' is in use by either parents or siblings. And the chromebooks are relatively easy to lock down to basically only allow things like google docs and nothing else.
Edit: They're all either 'scratch and dent' or 'end of life' which means they won't get further chromeOS updates. If you just need something very basic though, it could be useful.