Wilbur,
I'm coming late to your post, but with a point that hasn't yet been touched on, namely an important option for you if you get to the point of having the coach inspected. That is, like all the other engine manufacturers, Cummins has a network of service centers across the country, many of which are in a sub-net of 'Coach Care' Centers that also cater to RVers like us. I'd recommend strongly that if you have the coach inspected, you take it to one of these places to have the engine & chassis inspected.
We did this wnen we bought our coach, a 10 year old coach then with a 110,000 miles, a dozen or so years ago in Oregon, and since then the engine/chassis have performed flawlessly.
Cummins can't guarantee you won't have problems down the road, obviously, but they will at least be able to tell you whether there are any significant problems and the overall condition of things.
Overall, our costs have been directed much more toward the 'house' side of things (upgrading, mostly), than to the chassis & engine.
Best of luck!