Take a look at Supercircuits.com They have many cameras with many different specs. 130 - 170 degree field of view is fine. I have a 0.0003 lux, which is probably 3 orders of magnitude more sensitive than you really need, (try something at 0.1 or less) as you will have backup lights on which will provide significant illumination. Also, black and white works very well, you don't need to know the color of the Toyota you're about to crush, just where the Toy is.
You can find some reasonable to hot cameras there from $39 to $150.
Cheers,
AVNAZ