I taught a friend of mine about strategic couponing. He never did it before. Anyway, he was amazed that he was able to buy 14 TGI Fridays frozen snacks PLUS 4 bottles of olive oil for only $3 total. Actually he could have done even better than that but it was a good start.
I am too busy selling stuff I find at garage sales and auctions to mess with that, but if you were good at it you could make a little bit of money selling cosmetics and stuff.
Vanderbilt 1914 Yearbook bought with a box of books for $1.00, sold it for $63! I love obscene profits.