So I've been looking around for helmet cams.
"twenty20":http://www.twenty20camera.com/helmetcamera.php has one that seems pretty good to me. There are cheaper ones, but most of the cheaper ones only do the small video size like digital camcorders. If you want 640x480 size you need to spend at least $200.
Sadly my camcorder doesn't have video in so we'd need a recorder. "This one":http://www.amazon.com/exec/obidos/tg/detail/-/B00008VFCU/ seems like a pretty good deal. It's not perfect, and we'd want better in the future, but it is cheap enough that I think it could work until the good high capacity ones get cheaper.
Total thats about $375. For about 2 hours of video. Plus the recorder can use CompactFlash cards so once one is full you can just put in another one.