I know Circuit city has some backup cameras and Walmart does also. Both are in a pretty decent price rage. I think Best buy also has them (haven't looked for them there, but think I've noticed them before). All of these would mount at the top of the license plate.
Because all of my windows behind the front seats are blocked, I've been thinking of doing this same type of thing.
The "cheapie" options will give you a backup camera and that's it (all I would want/need). The more expensive options allow for playing videos and such.......all the way up to some REALLY nice gps/backup camera/dvd playing/flip up monitor in dash stereos. I'm not in the market to spend upwards of $2k for all of that though.
A buddy of mine put a system like that in his vette. Truly is a nice option to have "all in one" but a bit much (in my opinion) for a vehicle.
