Transport costs contribute to the higher price. The closer the dealer is to the factory, the lower the transport costs. That's one thing which contribute to higher price, the other is how greedy the dealer is (how much profit to they want to make)
An RV from Northwood Manufacturing or Outdoors RV (both in LaGrande, OR) will have a much better price from one of nearby dealers as opopsed to one on the sat half of the US.
There's two local dealers that have very good prices and ge buyers from all over the US. One is probably 2 miles (or less) from Outdoors RV and about 6 miles from Northwood. The other is over the hill in Pendleton. Both dealers pick up their own units from the factory, so there is no "middle man" transport company involved.
An example of dealer markup is very obvious for several dealers on the above brands. Sumner RV (in Sumner, WA) is always higher than RVs Northwest in Spokane, and Apache Camping Center in Tacoma, Portland and Everett - and not just minimally higher to make up the slightly higher transport costs, I'm talking like thousands more.