Play are selling "Lego Star Wars Complete Saga" for both the Xbox 360 and Sony PS3 for £24.99 (inc Del.)
You can get cashback through the usual sites (e.g. 4% Quidco, making them £23.99 each)
If you use the attached 5% voucher + Quidco, they're £22.79 each.
Next best prices are £28.99 fro the PS3 (ShopTo) and £27.99 for the Xbox 360 (Gameplay).