Welcome to SC, hope you have fun here.
Well, this cheat disk you speak of mght be an Action Replay, and depending on where you live, either in the US or in the UK or wherever, the stores and product supply may differ. But if you live in the US you can go to EBGames or Gamestop and buy one they're only like $20-$40($20 for only CD around $40 for CD and Max Memory card.). Hope that helped, but if you need more info then just ask, somebody here or even I might know something.
Previously Lycanthrope
XBL GamerTag: GunChaos617