Back up camera systems

I have come to the conclusion that I just cant judge the distance from a vehicle behind me when I'm backing up.I'm not sure if it's me just not used to the new truck or what but I'm leaning seriously towards buying a rear view camera system to aid in backing up plus in trailer hook ups.I have searched but didn't find much info and was wondering if anyone can offer a recomendation as to a good unit that is not too pricey but worth buying.

I have a Peak back up camera that I got off eBay for a good price. You can find them for $99 but I think I paid $69. They have three models...they are all the same except for the monitor size. The 2.5" is s bit too small but the next size is perfect, about 3.5. They have a 7' model but it's just too big. We use it in our horse trailer since the connection from the camera to the monitor is wireless. It was easy to install with just a 12v connection and now we watch the horses as they are traveling to make sure they are OK. They eat their hay and look out the window and generally just chill.