How much should a pre-sale independent inspection cost?

I'm interested in a 2002 R-Vision 211s, located about 500 miles from where I live. Before making the trip, I would like to get an independent inspection. I found an inspection service relatively close that charges $500 flat fee for RV inspection.

Is $500 a reasonable price for an inspection?

The pic on their site is of a class A, I'm wondering if a small motorhome inspection would cost less. There is a sample inspection of a car on their site, and it seems very well done. This outfit advertises inspection services on cars, trucks, & RVs.