This is the cheapest i've seen anywhere for this. It looks like it's only available for store pick-up, so i'm not sure about widespread availability unfortunately. Worth a try though :)
Also includes free game and Xbox live trial.
# This camera seamlessly integrates with the Xbox 360 system and the Xbox Live network to bring interactive social gaming to life.
# The camera allows gamer's to personalise their gaming experience with their own unique gamer picture, send photo message and chat by video, in and out of game with friends and family over Xbox Live.
# Includes headset, 1 month free Xbox Live trial subscription and free game 'Uno'.
# Size (H)6.5, (W)5, (D)6cm.
# For ages 3 years and over.