So that you can then trade them in to a record store?

I've decided that there's a lot of CDs I never listen to and I'm going to sell them back but a few still have the stickers from when I originally bought them, from the same shop. How do I get rid of the mark that peeling off the sticker leaves? You know, that gooey residue stuff.

Also, how much do you think they would give per CD? These are some pretty good, highly esteemed albums.

I've never done this kinda thing before.