The previous owner of our '05 PT had the backup camera replaced with a wireless system.  It now works sporadically, and I have been unsuccessful correcting the problem.  I am very uncomfortable driving with the backup camera screen blank about half the time.  so, I am going to take the system back to a wired setup.  I have confirmed that the original system is still functional.  I bought a $15 camera and hooked it to the wiring in the rear of the coach and everything worked as it should. Because the conversion to wireless process fiber-glassed over the original camera port I figure the easiest path is to mount the new camera on the exterior where the wireless camera is now.  I spoke to Mark at RV.cams, who was very helpful.  His best solution is to use a Voyager VCMS155 camera.  It can be connected to the original system with the aid a a couple of adapters.  Cost will be about $250.
Has anyone else used this camera?  And, I don't mean to sound cheap, but, is there a good solution that is cheaper?