I bought a kit from Amazon. It's the Crimestopper Backstopper CA 5011. I haven't done the install yet, but It comes with everything you need. It gets power by splicing into the reverse light. Seems like the hardest part is getting the courage up to drill into your bumper. I plan on installing next week...will post pics of the install and share thoughts about how well it works.
If you do a search, there are a couple threads about the topic
This is the system I have:
http://www.crimestopper.com/Backstopper/ca-5011.html
