I always wanted one of these for surfing, but didn't really know how I'd use it. I'm not good enough to do the arm hold, fall enough that it wouldn't last on my head... Wasn't sure about mounting on the board. For the long boards it'd be okay, but my 7'4" board I'd proably end up eating the camera one time.
Other uses I didn't do anything worthy of spending $$ to record, but if the cheap one is decent then maybe I can justify it. Or it's justification to start doing more neat things that are worth recording