Oh I keep everything, unless a friend wants a game that I no longer use, then I will let them borrow it or just give it to them. Problem about selling things back is you generally get next to nothing back, and I would rather have the ability to go back and play an old favorite than have an extra $5 to $15 that I could easily get through other means. As far as selling things in the long run, unfortunately that isn't too profitable really. Old consoles don't tend to sell for much, and old games generally are only highly valued if you have them in the original box and sealed. If you do happen to have any of the Pokemon games for the Gameboy or Gameboy advance still sealed though, those tend to sell for $200 to $300