This guy's got the sharpest aviation videos, taken with a compact camera, that I've come across on Youtube. He's using a Canon Powershot S80 (came out in 2005 I think).
I would expect there would be a newer version however I haven't done the research on it.
You can pick these up on Ebay, used, for about $100 US.
Just for example, this video shows you the top of the line, RED digital camera.
Make sure to click on the red 'HD' symbol, bottom right or else you'll just see your everyday quality video.
The video starts off a little slow. You might want to skip ahead to 1:42 point.
The aspect ratio is pretty striking; 16:9, which I think you can now find on some compact cameras.
Camera and lens cost about $25,000 - $30,000 just to start.
It's being used to shoot professional feature films.
Afghanistan in RED ONE 4K High Definition