You are paying for the bag and filter. No matter where you get the camera from you hve a 2 year warranty and the same with the cash back.
http://www.calumetphoto.co.uk/item/355-581A/
Camera for £378.98, 2GB Card £20, Crumpler Bag £50, Filter £13. Still a good deal none the less
But again I say go for the D40 and get the 50mm lense