About the only place you will find a used slide-on camper is on the back row of a 3rd tier used car lot. And wanting a particular unit further reduces your chances.
RV dealers don't like to sell rigs that are more than a few years old for some of these reasons:
1. Warranty... when a dealer sells an RV the buyer expects some follow up when something breaks in the first 30-90 days. This is the entire reason that my local RV dealer, one that I know well, doesn't sell anything over 3 years old.
2. Depreciation: When a RV buyer comes to a dealer and sees a new trailer for $20,000, and a 5 year old one just like it for $6000, it's that much more difficult to sell new ones.
3. Consignment Costs: If a dealer takes in a rig on consignment, they have to take at least a 35% mark up over what they give the owner. Most owners aren't interested in those margins and there is no money out there for dealers to "float" used inventory.
There is an RV dealer Medford, OR that we stopped at a few years ago that had three used slide in campers for sale
, all were less than 3 years old and all had been repoed from the original buyers.
Save your gas money and try the phone and the several web sites available. You can also post a "Wanted" ad and offer a small reward for any leads that turn onto a sale.....