A solid 1080p projector will set you back around 400$ new, even less used - that’s for a reputable brand. I’d say they’re cheap to the point where bothering with potential Chinese crap isn’t really worth it… And these can do 100" from a distance of about 2m - that’s for long throw models. Short throw projectors can do the same image from right next to the screen, basically - depending on how you plan your setup there are options.
If you’re just getting into the topic you might want to read up on DLP vs 3LCD as well.
Yeah it did cost about $400 dollars and it looks great, thank you.
Anyway I forgot to include the price of the screen in the $600 estimate so put it up to about 700. And the screen size is 120 inches. It could handle larger actually but I can only work with the size of the wall. Sorry the fact that it wasn’t a brand you expect doesn’t conform to how shitty you think it should be.