You can buy one COD 5 and get one free!! if you sell your extra copy to cex they give you £14 cash making the total cost of the game £25.99. Other retailers may offer more making this game even cheaper!
This is my 1st post, hopefully it helps!
Other games you can choose from on PS3:
WWE Smackdown vs Raw 2009
Prince of Persia
Tony Hawkes: Prving Ground