What the dealer will accept is going to depend upon the circumstances. Normally 25% off is a good average on a new unit but leftovers will vary substantially.
If a dealer gets a unit in at the end of the model year he gets it at last year's price. If he sells it based upon last year's price you are already getting a better deal over the higher 2006 MSRP. If the unit is a popular unit he probably won't budge that much.
However, if he's had the RV on his lot for a while it may be because it's not the most popular floor plan, not quite the right color or decor, or has been eclipsed by a new and improved model that just came out. Now he has a unit that's going to be harder to sell and he's in a tough spot. He's going to want to move it so on the one hand he's going to lower the price to get it off the lot and invest those funds into a different unit so he should be ready to deal. However, he doesn't want to lose money on it and he probably has financing costs stuck into it from his floor plan interest so he can't go as low as he would like. But, the longer he sits on it, the more his cost becomes because the interest keeps on building up. So now he's in a tough spot and every dealer thinks differently on how low to go. Generally it will take some negotiation over time on your part to get the bottom dollar price.
Most important is to ask yourself what you think about this coach. If it didn't sell before it's probably for a good reason. Will you be happy with this particular RV? If not, you'll be trading it soon for what you really want. In that case the depreciation hit you'll take at resale will more than make up for the extra discount you got up front so I'd seriously consider this before looking at price alone. If it's just what you want and you can get it for a great deal - go for it.
Mark & Leann Quasius
2016 Cornerstone 45A
2007 Allegro Bus 42QRP (Sold)
2012 Jeep Wrangler Unlimited - Rubicon