I couldn't believe the prices for the guitar and drums either when I decided to sell my extra instruments over the summer. I guess with them no longer available in stores for the most part, and the guitars and especially drums wearing out with a lot of use on the higher difficulties, people are looking to replace them. I agree that yard sales are probably a good idea. I was going to suggest Gamestop but then I thought I remembered reading they didn't take in the guitars for trade in so they probably don't sell them either.