Best resource I have found is at www.tadibrothers.com. They sell in addition to monitors and cameras and complete kits, video signal amplifiers ($50, $100, $150 depending on amplification) that work with any camera and monitor.
For the Garmin 760 there is the Garmin BC-20 camera that is compatible and will hook up to the Garmin with a special video receiver that clips onto the back of the 760. Distance is limited to 45 feet without boosters but it results in one 7" display working for both GPS and for monitoring the video camera. I did not want two 7" monitors on the dash while driving.
I wired the Garmin into my running lights so I don't have to be backing up to have use of the camera. It works well and a single touch of the GPS screen switches it to the video display or back to the GPS display.
