I have also been in this situation. My thinking is on the 2007 was it should be a REALLY REALLY good deal (priced more like a 2007 used unit) because:
1)When you drive away in it there will be two (2) years of depreciation involved. (Look up the value of a 2007 unit as the 2009s are already out.) You know when they (the dealer) want to sell a unit it is brand new and worth every penny of the sticker price. But when you want to trade it in (maybe not even a month later) he gets out the blue book and tells you the sad news.
2)The tires, batteries, etc. effectively already are 2 years old. Their lifespan is based on age not use and that's a substantial percentage of their perceived lifespan.
3)The engine, generator, air conditioners, refrigerator, etc. have probably not been run for 2 years. Any mechanical item not operated or run on a regular basis is subject to premature failure (IMO). The seals, bearings, etc. don't get lubricated properly which can lead to many problems. Just the genset not being run regularly would cause the carb to gum up. (I know I have replaced/rebuilt a few in my time because I have been negligent.)
4)And remember there has been 2 years of people tromping through the unit while it has been on the dealer's lot. People pulling knobs, twisting latches, operating appliances, sitting on furniture. And oh yes, not to mention, their kids doing the same...
Sorry to sound so negative, just trying to be realistic.