So far, I have done my own work on our 1998 DP. Yearly cost for maintenance has been about $1500, but that is way beyond the future anticipated. Since we bought the coach three years ago, we have had a lot of "coming due" and "once in a long while" maintenance, including transmission fluid and filters, hydraulic fluid and filters, air dryer, air bag and shock replacement, front suspension bushings, new radio, all batteries, roof paint, etc.
None of the work I have done has been more technical than it would have been on a car. What is different is giant torque specifications, big and heavy parts, and a surprising lack of space for working.
Some things you will need specialized tools - tire replacement, brakes, etc. I will probably hand it over to pros. BTW, use your auxiliary brake. We have about 100K on our coach, and about 1/3 to 1/2 brake shoes left!
When some things break, you can be in for a serious investment. I have read of repairing hydraulic system repairs running not far under $10K due to engineering new parts into old systems.
I saved over $500 on a transmission repair by having cash in hand - be sure to have a resource for cash and/or expensive surprises.
If by new you mean new, you will not have some of these worries. As an observer, I have seen a different issue - a free warranty repair that takes three months, or $500 cash out of your pocket and on the road in a day or two.
Matt B
oldMattB
1998 Monaco Windsor