The rrp is only £18.99 for this set it has only 185 bricks. With this set you get 4 mini-guys about the size of your thumb, and a horse. And a weeny little castle. Lego has the 'Prison Tower Rescue' set for rrp of £45, which is twice the size (365 pieces + a princess + 4 knights + horse), and may be better value, if you can grab one. It is also worth checking other Lego outlets and comparing prices.
It is worth knowing that Lego are selling off their lego Kingdom sets - which is a generic 'knights, princesses & castle set', the whisper on the street is that a new Hobbit or 'Lord of the Rings' range may be on the cards for release sometime in the summer, just before the new Hobbit film release (December). So it may be worth waiting for the new range rather than shelling out on uncompetitively priced 'Kingdoms' sets, if you are buying this as a toy to be played with, as opposed to being a toy collector.