First, that price is no bargain. $15k would be more reasonable. $19k isn't beyond reason if the condition is really great, but I'm inclined to think the dealer is taking advantage of your inexperience. It's not too late to do some price negotiation.
Next advice is too check tire age and battery condition. The tires can look good and have plenty of tread left, but tires also get old and essentially rotted internally. 10 years is the max useful life of a tire, so anything in the 8-10 range means you will be spending big bucks on tires soon. Depending on the tire size, maybe $2000-$2500. Tires have a date code on the sidewall - check it. That coach probably has three batteries too, one for the engine and 2 for the "house". Another $300-$400 if not nearly new.
Tire date codes:
http://www.rvforum.net/joomla/index.php/27-maintenance-items/202-tire-manufacturing-date-codes
Also make sure the generator runs for at least 30 minutes under a load, e.g. a electric space heater of an air conditioner.
We have RV buyer checklists in the forum Library - suggest that you get familiar with one of them. Buying an RV is like buying a furnished house - you need to be concerned about leaky roofs, faulty windows, working appliances, state of plumbing and electric, etc.
I don't know what a PPI inspection is (PDI, maybe?), but if the lendor defined it, you can be sure it is intended to protect the lendor's interests, which are somewhat less than yours. It probably covers the major appliances function, but not things that might soon cost you maintenance money.