Just popped in to my local HMV (Worcester) and saw both of the above going for £9.99 in-store. They are the same price online, but why bother waiting when you can grab it there and then?!
These come with the GUITAR GRIP, the GAME and a plectrum STYLUS thingy! (I presume both versions have the same hardware in the box).
10 quid... bargain.
Will just point out - this will only work with the old phat ds and the ds lite - NOT the new dsi