Need new backup assist electronics, best place to look?
 

I believe that the electronics are responsible for the malfunction of my backup assist and I need some advice.
Is the components located in the trunk the bulk of the electronics or is there something hidden somewhere else that I am not aware of?
What should I reasonably pay for a new unit (I'm in the states) and should I even consider the dealer, or try an online store?
And most importantly, does that little black box in the trunk have an official name that will help me look it up easier?

Here's what I found in the JEPC. Hope it's some help