Regardless of age and experience one can easily be swayed when looking at RV's. This is a terrible thing to say, but take everything a Rv sales person says as hearsay, check everything out. There are lots of good used units out there, ones purchased and seldom used so low mileage and new like condition, take your time. Floor plan is very important, you'll regret a good deal on one if you are constantly wishing it had this or that feature.
Finding the actual value of a used unit can be found using Kelly Blue Book along with PPL motor home sales. PPL sell MH but also list, got to search there site, the sold price for units sold in past 2 years. This will give you a good starting point.
Once you determine the actual value of a unit don't be afraid to make a drastically low (in comparison to asking price) offer. Of course if your buying from a dealer you'll have to figure their cost of a PDI and anything they repair before you pick it up, but start low!
Good luck, have fun during this stage of the hunt, visit camp areas and talk to campers and what they like or dislike about their units. Most love to talk about their RV.
Tim & Mary Discovery 40X. Chevy Tahoe. RVM32
"I've been lost now, days uncounted..."GFR"