First, the Country Coach has good bones. The coaches are steel framed, sturdily built and fully featured. If the coach has not been abused and has been reasonably maintained, I don't believe you can beat them.
As with any coach, maintenance is the key. Pay a qualified diesel mechanic to inspect the running gear.
As to coach systems, make sure they all work. The Aqua Hot/Hydro Hot is a wonderful heating system but needs maintenance to perform well so check it out.
Bottom line, from my experience you need to plan on spending at least $2000 getting the chassis fully serviced since dealers don't do much of anything other than maybe and engine oil and filter change. Things to consider getting done are air dryer filter change, Allison tranny service, rear differential oil change, chassis lube, new serpentine belt, fuel filters, hydraulic fluid filter/s, generator service (fuel, oil and air filters, oil change), engine air filter, etc.
The Magna is a great coach.