Quiet AND mobile?
http://www.bridgecitytools.com/defau.../gyro-air.html
Cost is $1k above your stretch point, but the stats on it are very good. And whatever one may say about Bridge City Tools, "low quality junk" is not one of them. I have no experience with the unit, but am very, very intrigued. Heck, the only two things that keep me from getting one are power requirements (only have a single 220v available) and to a lesser extent, cost.
It came to pass...
"Curiosity is the ultimate power tool." - Roy Underhill
The road IS the destination.