[Update - It's £13 on Amazon. That's a bit stupid. Thanks, tenthousandgothsonacid.]
Play.com is offering LittleBigPlanet for £17.99, which, in the parlance of the gutter, is fucking cheap.
Tesco, not be outdone, has gone even cheaper: how does £17.96 sound?
So you probably won't buy it from them, then.