I got a wireless rear backup camera for around $100 from amazon.com .  I think the brand was Peak, like the antifreeze. I've had it about 3 years now.  It works OK.  The only complaints I have are that it is prone to interference from things like traffic counters, wireless cameras and the image looks washed out in bright sunlight.  The monitor is an over the mirror type and the camera itself is meant to mount on the license plate, though I had it mounted on the bumper.  I had mine wired so that it is on when the lights are on.  This way, I can make sure that the towd is still back there.