The way you ask the question is difficult to answer. If all maintenance work is done by others like Prevost it will be a little pricey compared to doing your own work or having your own employees do it.
Then to confuse it further what are your standards? Do you replace tires when they age out or do you push them risking failure? What about air bags? Brake chambers? Valves, etc? Some do not do preventive maintenance but wait until something leaks or fails. Do you do fluid and filter changes to a strict schedule earlier than what is called for or do you push the limits? Some folks think nothing of going far more years on coolant or transmission fluids.
I never ever want a roadside repair so I change perfectly good parts based on evidence I have gathered that suggests a safe life. I think my maintenance schedule is in the articles section and knock on wood, it has served me well. Costs are defrayed because I am doing all my own work with few exceptions.
Truth be known, Unless a coach is an older vintage your annual depreciation is going to be greater in cost than everything else combined.