Yes, the dealer does pay the shipping cost (not the mfg) and for us on the West Coast, we pay more since the majority of rigs are made in Indiana and brought to the west coast literally one at a time, so there's a lot of gas to buy for the more than 2,000 mile haul. When I was shopping for my new trailer, I got quotes from RVwholsalers.com and RVdirect.com and both had shipping prices of $2,500 to $3,000 to my door. They're both back east and the trip was about 2,000 miles or more to the west coast. Even with the shipping cost, both of them had the best prices by far. Long story short, I got a local dealer to match their deal and I ordered the rig.
So you're not necessarily getting ripped off by the dealer when they add shipping just be carefull that they don't pad it too much and look at the overal "package deal" as noted by others above.