Good deal?

Find out how old the tires are (years and miles), plan on a complete service of all fluids (including brake fluids) and all filters (engine and generator). Battery ages and type but I would budget new ones in most all cases. I think for a private sale the $ amount is too high to start but if you take that price and subtract what it's going to cost to bring it up to par you might find some mutual ground. Every coach loses value everyday so the sooner she can get rid of it the better off she will be.
I agree that buying from anyone you intend to continue a relationship with is a very big mistake. However, if you both understand what is and what is not you should be able to continue to get along.