Wario: Master of Disguise for the nintendo DS is only £20.49 @ CDWow, but by using one of the £2 off games links, you should be able to knock this down to £18.49 delivered. Cheapest elsewhere is about £26!
HOW - click the £2 off link below, hit "Click here to go shopping" in the middle of the screen, then search for Wario: Master of Disguise!
Details: Wario: Master of Disguise sends the greedy Wario back into a new 2-D platformer - one with a unique touchscreen control system. When Wario sees a television series about a thieving master of disguises, he dives through the TV screen, steals the thief's quick-change wand and takes over the show. Break into exotic locations, from a luxury liner & watery ruins to an Egyptian pyramid, all in the hopes of grabbing as much treasure and loot as Wario can carry.