Ufo corki is not available as a skin code :) All accounts created before January 14, 2010 received corki and UFO Corki for free, and there is no other ways to get it.
Just letting you know! anyone trying to sell you an ufo corki skin code is a big fat scammer. So be careful! :)
Good luck in your hunt for black alistar though. I've seen quiet a few people selling it here on the forums. So i would be careful who i deal with if i was you. :)
Best regards //SpendingUncle