If the owner does not have receipts on the regular maintenance schedule, I'd add some preventative maintenance into you budgeting too:
-New belts
-Belt Tensioner
-Replace the radiator hoses
-Replace the Thermostat
-Replace the Air Cartridge Dryer
-Differential fluid change
-Tests Radiator Fluid, if bad, and not already, change one to an OAT based coolant
-Full LOF on chassis
-Full service of Generator, replaces hoses, fan belt, thermostat
-Hydraulic fluid filter and fluid changeover
-Aqua/Hydro Hot test for proper mix, drain flush refill if in question
-Should have Transyn in it. Which may still be fine. Pull an sample and send in for analysis, and see what it says
(Lots of the above may not be needed, if the owner has documented history of repairs. Hoses are some people wait on, but I had our hoses replaced preventatively at age 12. Yes, they seemed to still be OK. But I prefer to due maintenance change over's on my time and schedule, vs while out and traveling.)
Adding to the other posters comments:
-Look at the radiator. If the side caps have bolts on them, or if you stick a magnet up and it attaches to them, then you do not have one of the suspect aluminum radiators
-Yes to check the engine SN on the Cummins Wrist Pin range (The Cummins section has a sticky with the SN ranges.)
-Lots to read up on about tires, but agree with Don's listings. I've seen some owners put Hankooks and or Toyo's on the rear positions. And Michelin on the Steers, to save some budget. But I also would have know hesitation putting Hankooks or Toyo's on the Steer positions as well. (Toss Continental and BF Goodrich's ST230 into the mix of tires to consider, both FMCA discounted too.)
-Shocks. At least to start with on the Steers, many are very happy with the change over to Koni EVO 99's
-After you get out and drive it some, if you would like to improve the handling and suspending setting faster on mountain S curves or emergency maneuvers, the Source Engineering Comfort Control Valves do help on the air suspension
-If going to the Samsung RF18 route, which we enjoy a great deal in our coach, also factor in battery capacity. It may need to be bumped up. And determine if you want to add a second dedicated Pure Sine Wave Inverter to feed the Samsung.
As you can see, all of us are more then willing to help you spend some coin. But I also assure you that other then getting the mechanical items up to snuff, and tires too - the rest can be phased in. To save coin. (And you will need to, as if this is your first CC - it's mandatory to slip a nice bottle of scotch over to each CC owner you meet on the road the first time. (Let me know your travel plans, and we'll arrange for a handoff.))... Go use the coach, both of you start thinking about what modifications of interior and or mechanical that you might want to make in the future to make it 'your coach'...
And don't let the gang, especial this long winded poster, spook you - these are marvelous coaches. And if you take good care of them, they'll take good care of you. A person in the park we're at now, had a new SOB coach, mid tier (And I won't share the name to avoid conflicts.) - after three years of traveling, and twice back to factory to have fixes to fixes taken care of, and then fail again - they'd had it. They still had a Sticks & Bricks home, so the owner did a major detail to his RV, and sold it on Craigslist at full asking price within two weeks!). He and his wife had originally been considering older higher end CC's/Newmar's/Monaco's. It took them 5 months of searching, but they're now very happy with an 03 Magna with C12, 3 Slide coach... They've done next to nothing mechanically on it since they bought it, as the previous owner had full documentation and maintained it very well. They're doing some interior refreshing, adding another cabinet in one location, changed some cosmetic things... And said after just one 1 year of usage, that they know they made the right decision. The difference in quality, the solid foundation of the chassis - etc...
I hope this coach is the right one for you. If not, keep looking
!
Best of luck to you both, have fun along the way,
Smitty