I bought one of those "First Act" guitars WalMart sells for my grandson at a thrift store for $5.00. I don't claim it, but it lives at my house. Hard to fret, has lousy intonation, but tune it to an open tuning and it's a purty funky thing to do some slide on.

And I bought my first nylon-string guitar for $15.00 from a guy who came into a bookstore I was working in. He wanted to sell some second-hand books, but they were all junk. He was pretty hard up for cash, so he sold me the guitar instead. It wasn't much good, but it sparked enough interest in playing on nylon that I soon bought a better one. I think I gave it to a friend.