Ion Speed Pro. Check Amazon. Usually available for around $60. At that price you could get two for your stated $200 budget, and run 'em facing front and rear.

Weatherproof as-is. Simple to operate. Durable. Reliable (although picky about media cards -- any problems I've had were resolved by switching to another media card). I've had one for almost two years and use it on almost every ride.

Runs about 90 minutes per charge and can be hooked to an external battery, although this requires removing the weatherproof rear cap.

I use it mounted to the stem on my road bike, and helmet on my hybrid and errand bikes.