I have two friends that have bough their use coaches in the resent past.
Friend #1 is the kind of guy that if the thing works leave it alone, he has done some electronic upgrades but that's about all. in 30k miles he has done a couple oil changes and a set of tires.
Friend #2. If it is dirty, or not todays technology he changing it out. He had a cabinet hinge that didn't work well, now he has a whole new cabinet. His coach is always broke, and he is always bitching about it. How much has he spent? God only knows, but it will never be right for him.