I use a Sony HDR-CX760V that has a 1/2" chip and a 10X optical / 17X Extended lens. I added a Raynox 2.2X telephoto lens to get 37X total. Current model of the camera at B&H photo is $999 and the telephoto lens is $235.
Under that, Sony make a 1/3" chip camera (HDR-PJ430V) with a 30X optical / 55X Extended lens for $599. You wouldn't need the telephoto lens. There are cheaper cameras with smaller chips under $300.
The main things to consider is the chip size (bigger is better)and lens. It seems the better the camera, the less zoom the lens has (most users are filming close up, not long distance). My setup with 37x is still not enough sometimes.
On the Sony's, the Extended zoom does not lose any quality. This is not the same as digital zoom which is poor quality.
Hope this helps.