There used to be a TV show on discovery channel about how to do B&Es in your local boujee neighborhoods. I think it was like a bar rescue thing where they would go over home safety at the end with the owners. Anyways, good luck with your search.
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.
Oh, this really small obscure town next to my parent's tiny obscure town has a great retro furniture store with a town of nice mid century stuff at reasonable prices.
If I were you I'd try there. Other than that, it's fast fashion for furniture, and I hate it so much.
(looks around my house) wow literally every piece of furniture I have I got for free, except for my bed frame and my computer chair (the first bought on Amazon, the second bought from an Office Max).
Some of the furniture I own (specifically my bookshelves and my desk) is shored up with a few extra screws and wooden planks that I put there too, because even cheap ass-furniture can last a lot longer than you expect if you put just a little effort into repairing it when it breaks.
If I had to get something (and I couldn't find it on OfferUp, FB Marketplace, or Craigslist) the next place I'd check would be Big Lots.
We recently moved and had to furnish a whole new house. We had some minor stuff of our own from before like a desk, an office chair, some drawers and a TV, but not even a bed otherwise.
Save for a new bed matress, we bought it all second hand, off local thrift groups, in thrift stores etc etc:
nice hardwood bed frame for $30
a beautiful vintage "rococo-style" desk for $80
two vintage chairs in the same style for $30
this one is more expensive, but absolutely beautiful: a copper-plated coffe table with a world map motif for $100
vintage 2 person sofa, still same fucken style, $50
vintage drawer $40, another one in a different style for a different room but also similar price
rustic kitchen table $40
6 fitting chairs for the kitchen $40
cute corner cupboard $10
free bookshelf
...and more. We are now fully furnished, and really nicely so (seriously, it's beautiful furniture), and it all went for under $700. Now this is over like 5-6 months and took us a fair amount of looking, but we needed to just browse the thrift sites and have access to a car for easy transport, ppl offload really beautiful shit for cheap all the time.
Though now that I think of it, we did buy also a few rugs and some other minor shit that probably runs up like another $200 or so, and we got some old trash from my parents before we changed it out for better shit (and also, the thrifted kitchen chairs were found by them)
I don't have much furniture, but some I got used for free, and some I made myself. I think the last thing I bought was from Ikea, but it was one of the rare "not made of cardboard with a fake wood veneer" items lol
I've been building my own furniture. I've built a bed frame, a desk, kitchen prep counter top, and two bookcases so far. Nothing is fancy. They are all just rectangles.
For nice quality look for locals selling their old furniture. My roomate and I recently got a free couch made of real hardwood after talking to someone who owned a moped shop. It was old and not flawless condition but nothing we couldn't fix. Nice thick fabric too and the type of couch that you really just sink into. I think it has springs?
Anyway the nice shit isn't available to the working class from retail
I got a solid oak bed for £50 from one of the secondhand shops in town, and a £150 IKEA desk that's still solid after 7 years and 2 moves. Almost all the rest was donated, rescued, or stolen.
On the side of the road, the thrift store that still sells furniture, or build my own. I sometimes can afford flimsy stuff that's super discounted (and can be reinforced with some wood and screws in the right places) since my furniture budget is like 30 dollars or so tops.