Price vs. convenience. It always comes down to that battle. You sorta already answered your own question, in that you'll get lowballed on trade-in value and (on the flip side) you can get a better price yourself but there can be considerable effort selling it on your own. I second the idea of Craigslist... I mean it's free, what do you have to lose by trying? A few months ago I sold my 1994 Class A on Craiglist in about 2 weeks. I was pretty systematic and listed my ad in a new Craigslist city/site every few days, until I covered all the populated areas within a couple hours' drive (Chicago, St. Louis, and a few in central IL). Lots of calls/emails and a few visits, including the buyer who drove 2.5 hours (one way) to see it first, and then took the Amtrak the second time and drove the RV home.
#1 Tip For Selling - BE REALISTIC ON PRICE. That's the only way you will get it sold yourself, quickly. This time of year is a catch-22 ... a lot of other rigs may be going up for sale at the end of the season, increasing the used RV inventory and therefore decreasing the number of potential customers out there. But you might also have more people looking because
of the potential for deals, and you could find the perfect buyer.
I didn't mention Consignment because I don't have any personal experience with it, but some members here have reported positive results. It all depends on what's available in your area. PPL Motorhome
is probably the most well-known RV consignment outfit nationwide, moving a LOT of rigs out the door weekly... but it's in Texas.