From the Thrift Store Roadshow department:

Bob Hampton, of Blue Springs, MO, paid $14 for a watercolor painting he thought "was quite good for a print." Later he realized it wasn't a print at all, but an original by painter James Milton. When he had it appraised at Christies, they estimated its worth at $2000-3000. I've found signed first editions of books at thrift stores for a quarter and sold them for $50-75 before. If you are going by percentages, I'm the luckier one. (NBC 17)