As you can see on facebook Marketplace, from 50 quid up to 300 you can find many varieties of printers
https://www.facebook.com/marketplace/105543192811747/search/?query=3d%20printer
however, this is the wrong group for your quest if you intend understanding the sector.
This group is more appropriate:
https://grabcad.com/groups/3d-printers-makers-diy-hacks-solutions-and-post-printing-tools
and when it comes to the donation, I doubt it will happen, I know a few people that went that way and failed succesfully.
Do what I did, buy a cheap one knowing is crap, use it to learn as much as you can by making it work in the first place, than by bettering it untill you reach a limit, than you start designing and building your own.