You can actually buy the camera direct from here:
http://www.goprocamera.com/
For about 300Dollars, and it comes with the waterproof housing and various attachments to connect to your boards and helmet. I reckon its great bang for your buck. Though you would definately need a bigger memory stick if you want to record a lot of high def footage.
I'm dead keen on getting one, but also buying the line attachement so I can get a top down view of the riding.