I suspect that your system is probably very similar to the intec system I pulled out of my 2000 Holiday Rambler Endeavor in 2010.
I have no idea what it will cost for a shop to do the work, but if you're willing to do it yourself, you can be under $200 for a single camera single monitor system.
The intec system has a six conductor cable, which is more than enough to run a color camera to color monitor, but you'll probably have to do some splicing and soldering.
I installed two cameras on the rear so I ran new cables down the rear cap, along the frame rail, and back up into the coach. The two cameras give me a close range view (see front of toad and tow bar) and a long range view (see 3 lanes of traffic around the rear of the motorhome). You can accomplish the same functionality with one movable camera.
The hardest part of the project was getting the intec monitor out of the dash, as it must go out the back side and down to the floor. It can not be pulled forward and out. I was surprised at how heavy it was.
If interested, I have a word document with pictures and camera source that I can send to you. If you want it, send me a private message with your email address.
Fred & Vicki
St. Augustine, Fl.