I agree with those above who say you basically have to be a do it your selfer or have lots of money.
I cant imagine the frustration of having a shop do all the stuff that I have done even if I did want to pay them.
Cover the basics like roof seal, shut off the water switch all the time, dont leave with the campground water pressure on, dont leave the black tank valve open, etc etc and dont worry about it. There are a lot of things to pay attention to so make a check list of stuff to go over when pulling out and setting up.
As many have said before if an rv was built like your car it would cost $100,000 for a 20 foot trailer. Seriously your truck or car is like a space ship compared to the cheesyness of an rv. Look at the wiring in an rv compared to the weather pack seals used on almost everything in your car.