I bought one of
these.
I have an iPad mounted that I use for navigation, music, etc. and I use it for the display for my back up camera as well. All I have to compare the display with is the old monitor (it's a 2004 model) so the iPad display is obviously much better.
It's wireless, and at $110.00, the price is right. The iPad (or whatever you decide to use with it) has to connect to the camera's WiFi. First time connection time isn't bad, but it's not immediate either. So that's something to think about.