The dealer will always list a high price knowing the buyer will either pay that price (good for the dealer) or negotiate the price down to what the dealer is willing to sell it for (still good for the dealer). Or if the dealer needs to move inventory will let it go for a lower than hoped for price (good for the buyer).
Keep in mind NADA is a guide. When buying anything, I look through online resources like RVtrader.com, Ebay, Craigslist and others to see what dealers and private parties are listing like items at. I also pay attention to how long the item has been listed...longer listed means the price may not be where the market is.
Your best bet is to find an RV you like and set a price you are comfortable with based on research and then negotiate until you find a seller willing to accept the price. If you need the RV and can't wait then you try to get the price as close to your price as possible.
Dealers will typically say no 5 times before lowering the price to a price you are comfortable with.
