The internet is your friend in this situation. Do your research and walk into the dealership prepared and more than willing to walk out without making a purchase.
Remember that once you are face to face with the dealership, they have all kinds of techniques to make the deal better for them. They will read your body language...and know if you are in love with a specific RV.
I have had success looking at the online prices of large dealerships near where the RVs are built and then negotiate in the deal other perks such as throwing in a high end hitch or vent covers, etc.