Depends.....what is your definition of "Fair"?
A dealer is buying to resell them so they cannot give you top dollar.
They need a profit margin and that usually is more than some people feel is fair.
You will do better to sell them yourself if you want anywhere near what their actual retail value is.
Selling a used gun to a dealer is no different then going to a dealership to sell your used car.
If you are OK with accepting about 60-75% of the actual value for your guns then a dealer can cut you a check and get you paid fast. Selling them one at a time to individuals will get you more money for them but is also a pain in the butt, especially the handguns.
OK, after more thought it is like 45-60% of the actual retail.
But to defend the dealers, used guns and accessories are the only place you make ANY money. Accessories are in the shitter now too thanks to the giants like Cabela's, Bass Pro Shops and Gander Mountain.....that is good for the consumer but horrible for the small business (gunshop) owner. They have to try and make a lot on used guns.