I agree with donn above.
I installed a no name Walmart digital in each of my last three campers. Takes longer to open the factory packaging than to install. All your wiring is already in the wall. On the last one I don't think I paid $30.
Your dealer already knows what this will cost. Not sure why they couldn't quote you.
Dave, Judy & Daisy May
2010 Sierra 356RL
2011 Silverado 2500 4WD, LT, Ext Cab, LB
Duramax 6.6L V8 Turbo Diesel
Allison 1000 6-Speed Automatic Transmission