Hi, This is a tip i used today to get my self Guitar Hero 2 for £48.
Simply, go to a gamestation store, and within the store they will have the deal "2 for £40" on preowned games. The choice is vast, they have many good games, but the best ones are:
Gears Of War * Crackdown * Lost Planet
This is because if you buy any of the above two, i.e. Gears of war and Lost Planet, you can take them to Blockbuster, and receive a trade in value of £26 each! So that works out at £52 for both!
So then with that £52 store credit you can purchase another xbox 360 game or something else.
What i did was purchase Gears of war and Crackdown today from gamestation, took them to Blockbuster received a trade in value of £52, put an extra £8 through and Voila! I bought myself Guitar Hero 2 for £48! Surely that is the cheapest anywhere.
Also using this way, you could receive any new xbox 360 game for £30, because of you take one of the games from gamestation to blockbuster such as Gears of war, trade it in at Blockbuster, and pay an extra £9.99 for any new game!
I hope it helps someone. Thanks a lot.