How do think the dealers get rv's for the lot. They order them from the factory. The difference is when a customer orders one the dealer pays the manufacturer with the customer's money rather than the dealer's money. This saves them money. They will try to tell you doesn't though and will not willingly pass the savings on to the customer.
Late last year my trailer was totaled by my insurance. After going to shows and lots I decided on a model. Went to the nearest dealer that carries that brand and they had already sold the model I wanted and were not going to get another until spring. Asked for a quote on a factory order. They quoted msrp and were not interested in negotiating. Ended up get it from a wholesaler for about 38% off msrp including delivery fee from San Diego to Tacoma, WA.