What is your definition of cheap? My son has one for sale, on O2 so already unlocked, it's about 6 months old, has a slight mark in the top left corner under the screen and a mark on the side of the case wher he dropped it it but not detrimental to the phone, it all works perfectly. He's only selling as he got an upgrade to a 4S. Make an offer if your interested and I will ask him.
Leigh.