Just my $0.02. When looking for a used pop up, they came and went very quickly. Originally I wanted a grandby, but expanded my search to include other brands and longer options. When a 16 year old Cuchara posted 400 miles away, I called the guy and he had all the right answers. Maintenance was done on the roof, no leaks, systems worked, no structural or siding damage. I went to inspect with cash in hand and paid full asking price. I had to do some cleaning, and will have to continue the maintenance, but got into a fully functional and well-kept camper for $7k instead of $40k for a new one. The seller had five other folks waiting to see it if I passed.
I agree - if it looks like it has been well taken care of when you talk to the seller, go right away and bring cash. I have looked at several camper that have lasted more than a day for sale and typically they have some major issues. The two I bought had a line of folks wanting to buy them, so I brought cash and arrived as fast as I could - helps that I have a really flexible schedule and don't have to wait for the weekend like most folks.