Get a quote on a new one from one of the RV "wholesalers". Call them, tell what you are looking for. Give an example, like you did above. Any given dealer will have 10 brands of that floorplan as it is very popular. You can buy a new model with that floorplan for $18-$30k depending on what features, construction, etc.
Google:
RV Wholesalers
Lakeshore RV
Holman RV
RV Direct
I live close enough to those dealers that I could buy from them and pick up. For used, I would compare what those dealers sell for to local pickup customers and then consider the value of your time and $ to transport new vs. age/condition used.
I prefer to buy new and pay maybe 25%, even 50% more than used/2-5 years old. I get to order exactly the options/colors I want. No one else abused it, just my own kids :).