I don't think buying from a dealer necessarily gives you a better deal. Unless something is under warranty, the dealer is far more likely to charge you more for repairs than an independent shop (e.g., replacing door latch in my SUV = $300 at dealership; $176 at independent shop).
Because I take my RV to the same shop as my SUV for engine and chassis repair, I have a stronger relationship with them than if I took them each to the dealer I bought from - and the shop has more to lose by not fixing the problem.
While having a different engine & chassis shop from the RV house shop may be seen as inconvenient, I have not found that to be at all. The two shops I use are around the corner from each other. When I was having my dump valves replaced, the RV shop smelled fuel. I called the mechanic shop and let them know. When the RV shop finished their repair, the mechanic shop picked up the RV and fixed the leak. No more effort on my part and it cost less for both repairs than had I gone to a dealer. In addition, I didn't worry that the RV shop was "finding problems" that didn't exist to get more money out of me.