I don't expect this to blow anyone away as it's still pretty expensive, but if you're desperate for a copy, you can pick up a brand new copy from Toys'r'us for £42.99. It's priced on the website as £47.99, but by applying the code 8086839990, you can knock a fiver off. Eligible for free delivery too (although it says £2.95 at the checkout for delivery, the total says £0.00 delivery)
Hope this helps someone. I shouldn't have left birthday shopping until the last minute!