Found in a yard sale in Miami in a crappy frame, 5 small blockprints from Artist Ansie Uchima, all in mint condition, signed, dated, with series. In the back of the frame was a letter from him to the owner. Paid $7.00 for them all. Had them framed by a professional and two years later sold each one for $4500 for the five.
Boston came across a box at a yardsale of 1st edition marbelized cover books, paid something like $40 and sold them all at the antique book store for $2300
You can still find great stuff, just have to have a good eye and take some risk.