We bought our TT at our dealer and got a great deal, but I found out later that we could have gotten a better deal if we had gone to the show earlier in the season. I now help at shows with the same local dealer and have seen for myself some deals made at the show that I can still hardly believe. Things like a Great deal on a WDH, free AC, Free extened warranty.
The best deals can be had when you get a couple of dealers to try to win you over when they know you are serious. Go to a show, find what you like and get the dealers to start bidding for your business. You may be suprised at the amount of movement there is.
The shows that I work at have the benefit of locking in a show price and once you signed the pricing deal you can go to the dealer lot and get a show package price for up to two weeks on anything there that may fit your needs better ... it is a no lose scenario. Im pretty sure that if the potential buyer then decides that they made a mistake and changed thier mind the paper that locks in the show price is ripped up and there is no obligation.
I am not sure how some of the huge box store RV dealers work as I only work the show with my dealer because I really like talking campers with people and I make a little extra money. I have no idea what the mark up of an RV is so I cannot answer to that question if anyone were to ask.