I've gotten a few things from the street when college students move out, if you have a university or college town nearby and you know the right days there could be a plethora of pefectly good desks, chairs or whatever left outside. Like regul said I've heard people have good results on facebook marketplace but I've never used it.

They really don't make things like they used to also, talking about things falling apart. If you can get good quality vintage stuff I think it's worth it, I have a wood and metal office chair from the 80s that is rock solid, from goodwill for less than 20 bucks.