When buying a used coach, condition is everything. A good clean coach could be worth twice as much as one that was abused or neglected. The book numbers do not take this into account, but it is very real. It could mean the difference between a good reliable coach or one that is in the shop all the time eating up repair dollars. That good one is worth paying extra for!
As for an add-on slideout, I would pass. Slideouts have too many problems, even factory installed ones. I would not take a chance on a retrofit slide.
Marc and Jill, Wellington FL
2013 Entegra Anthem 44SL