Every time we change oil in our class C they charge us extra

I have had oil changes done in several states in the 9 yrs we've had our C. One place in Oklahoma charged $60. for 6qts oil and filter while in S. Dakota I paid $148. for the same job. I think it's according to the type of place one uses for the change. Some have their prices posted and that's where I'd try to go like others said but ask if there's an additional charge for your MH. I change mine every 3K miles if I can find a place to do it myself. Doing it myself only costs about $50.