Anywhere from $0 up into the hundreds. There's a bunch of different things that could cause it to not work and nobody here will be able to give you a dollar figure without some troubleshooting on your end.

 

Thanks for the info. I put in reverse and only the navigating shows. The camera won’t engage

 

Yes - some basic troubleshooting would help as it could be as simple as a reverse switch that's unplugged or as expensive as a failed control module. Do your reverse lights come on in reverse? Do you have rear sonar sensors and do they work? Many systems are tied together so this type of troubleshooting methodology will help diagnose the root cause.

Find the link here to download the factory service manuals and manual "AV" contains audio/visual as well as the rear camera.

-Eric