Gamestation are selling "Happy Feet" for the Nintendo DS for £9.99 + £1.00 p&p.
You can get cashback through the usual sites (e.g. 5% Quidco, making it just £10.44)
The next best price seems to be £13.99 from ChoicesUK.
Based on Warner Bros. Picture's animated comedy of the same name, Happy Feet invites you to put yourself in the tap shoes of Mumble, a young penguin born into a nation of Emperor Penguins, where each and every one needs a 'Heartsong' to attract a soulmate. Unfortunately for Mumble, he's not blessed with the greatest singing voice. He is a very good tap dancer, however...
So, as you step into Mumble's shoes - the feet of great contentedness as evinced by the game's title - you will experience his tap dancing birth, his harrowing escape from a hungry Leopard Seal, his fiesta-filled friendship with the Adelie Amigos, and finally to his climactic encounter with humankind.
The Story Mode in Happy Feet is where you'll find yourself talking to other characters, overcoming obstacles and collecting items to progress through the game. There's also a Free Play mode which includes Belly-Sledding, Fishing and the rhythm and timing-based minigames.