Slightly more than your budget but I've just fitted a Blackvue HD
Ran cheaper cameras for a while with expected results, but these are simply outstanding.
Usual full HD, but the real tricks comes with ability to work day or night-time, monitoring when parked up for bumps, Wi-Fi to connect to your phone for real time stream or controlling the camera.
Has GPS so you can capture a route play it back and see speed, times, overlay route maps to video.
You'd get something on ebay for £150 if you don't try fo the latest model.
http://www.blackvue.com/en/contents/sub1.asp?idx=27