Hiya,
I just clicked the "buy" button on two each of these:
REAR VIEW CAMERA NIGHT VISION WATERPROOF NEW FOR CARS
6 inch standalone headrest car lcd tft monitor screen
The cost is ~$156 shipped; pretty reasonable really!
The small mirror may get moved to the driver's side (to meet the the letter of the law)...so far I have liked how things have worked with it on the passenger side.