just picked one of these up in Zavvi was marked at a reduced price of £19.99 when i got to the till it scanned in at £17.99.
Not sure if these are available at that price online.
The kit includes a keyboard which plugs into the xbox controller and is very useful for typing on the xbox instead of using the on screen keyboard which takes absolutely ages.
It also includes a headset for speaking on line.
great at this price usually cost about £25
the link is: http://www.zavvi.co.uk/xbox+360+messenger+kit-games-Messenger-Kit-Chatpad-And-Headset/797169/qc.r10.1/p.jsf
if you use the 10% off online at zavvi you can get it even cheaper