Per Macworld, the top helmet cameras are as follows:
VIO POV.1.5: List price is $649.95, Amazon has it for $599.95 with free shipping and no tax in most states.
HoytTech HCR-100X (WEBSITE)
Oregon Scientific ATC5k. List price is $219, but it's being sold on Amazon for $129.97:
GoPro Motorsports Hero Wide: List price is $189.99, but Amazon has it for $166.23, which is a savings of $23.76, or 13%. Don't forget free shipping and no tax in most states.