Just been looking for Dead Rising 2 for the 360. Standard game has been cheaper but the price has gone up at Zavvi. This price £24.98 is for both the standard game and the Zombrex edition.
It's available online and in store. Picked my Zombrex edition up in store having phoned and reserved a copy. They also said they can order one in if they don't stock it. There is another deal posted on here for Tesco but seems there are issues hunting one down. Plus the Tesco stores in my town open the packaging and break the seals, so not so good if you're after a present.
Doesn't appear to be quidco online but you get 2.25% in store if you've registered a card on Quidco.