It depends on how often you drive it... we are weekend/vacationers, so we only put about 1000 miles/year on our Class A when we had it. I changed the oil once per year, in my driveway, used synthetic oil and a quality filter, and spent about $35-40 each time depending on whether I got the oil on sale.
If you are the type who does your own oil changes on cars (which I am), a Class A is simple. No ramps or jacks needed to lift it, because it sits so high off the ground compared to the average car. Despite its ease, some shops can get funny about RV's and charge you silly amounts of extra money because you said "RV". Many lube shop service bays are tall enough to handle big trucks and RV's, with space to turn around and pull in/out... some Walmart shops as an example. Even without the bays, the oil change could easily be done in the parking lot.
I'd call around first and ask shops what their standard oil change prices are. Then follow up with, "And your garage can fit RV's?" If they change their mind and then give you a higher price, hang up. Also scout out the shop and parking lot first to make sure you really CAN fit the Class A in/around. The smaller Jiffy Lube type places may not work.
