You love the GoPro Hero4 action camera, but it is way over your budget. A more economical option would be the Curve Prestige 100.
The Curve Prestige 100 has a uniquely design which allows digital video recording in situations where it may not be possible to use standard camcorders. Coupled with different type of adventure outdoor accessories, the Curve™ Prestige 100 will allow the user to capture high quality digital video and sound footage anywhere.
It shoots full high-definition (HD) videos at 30 frames per second. Unlike many action cameras, the Curve Prestige 100 has a 1.5-inch LCD panel that lets you see exactly what you are recording with its 170-degree wide-angle lens and 16-megapixel image sensor.
It comes with many accessories, including a bike rollbar mount and a waterproof housing to protect the camera down to a depth of 30m.