LeonaandLisa - FWIW: This was posted yesterday on another RV forum and pretty much sums up your question about maintenance / cost:
"Welcome to the world of owning and operating a motor home. There are two methods of recreation that are IMO more expensive, airplane and yacht.
I paid $2,600 to have the lift pump replaced. A bit over $3,000 to have the manifold replaced, both last year; OH, oil N filter(oil and fuel) changes for engine and genset was ~$500.
Did I mention traveling in a MH is the most expensive way? At our age however, it is the most convenient."