When you sell an RV, any "extras" you leave with the unit does not increase the sale value at all. Mostly, folks leave that type of stuff with a selling RV because they have no other way to get rid of it, or time is of the essence. So, as an incentive for a firmer sale, folks will leave stuff. But it still adds no greater value.
No doubt, the buying dealership took the extra "stuff" and discarded it, or used it as a free give-away on your old unit, or someone else's unit. If you left tools behind, more than likely they were attricioned into the dealership repair shop and never left the building. Once the RV was sold, it was out of your hands. They could do anything they wanted with it, even tear it down and resell it one screw at a time if they wanted to.
About your selling price. You agreed to the selling price. It makes no difference what the buyer was haggling behind the scenes with another buyer. Once the dealer offered the price and you accepted, at that point, it didn't matter who or what ended up with the unit.
About price, dealerships need to make a profit. Yes, they "buy low and sell high." That's how they make their money. Again, what negotiations they make among themselves is outside your deal. We traded our prior truck to a dealership and they gave us $18,000 for it in trade in value. One week later, we saw it in the lot for $30,000. I have no clue if it actually sold for that. I was a little pi$$ed over that, but then had to come back to reality and realize we had a meeting of the minds and I accepted the $18,000 price. After that, it was theirs. I had nothing to be envious over.
So, bottom line is, ... it is what it is. You got your agreed money for the sale of your RV. That's all that should matter.
