Disclaimer: what follows is my own opinion, nothing more.
In my mind, value depends primarily upon condition. If the house is clean and solid and in nice shape, and (most important!) there are no leaks or water damage, the asking price seems perfectly reasonable to me. If there's any significant water damage, I'd think long and hard before making any offer.
110K miles on the chassis is nothing to worry about, generally speaking. Wear items (shocks, ball joints, spark plugs, etc.) may well need replacement or servicing, but the basic drivetrain is quite capable of many more miles. However, that many miles often also means many nights of camping and many footsteps on the carpeting and many rears sitting on the cushions and so forth, so the house part could be very used and tired. That sort of thing can really only be evaluated by checking things over in person.
