Collectors firearms in Houston is about the most reputable fair place for a straight up no hassle sell to a dealer and not an individual.
They buy 'em to sell 'em. I wouldn't expect over $250-$275 from them.
The Glock would private party sale at one of the Relaint Center gun shows for about $350-$450, depends on who wants it and how bad.....
Dealers at the Gun show of course will screw you horribly unless it's something really rare and cool they can make a load on, other than that all guns are commodities to dealers, with no emotion attached...
I don't know how other states are but the cool things about gun shows in Texas are that in addition to the dealers any one walking around on the floor can buy and sell to individuals, as any citizen can any where in Teaxs, not just the shows, and it's a good place to find a buyer.....
If you ever heard of the gun show "loop hole" that's it....The only way to plug that loop hole is to forbid ALL private party buying and selling, not just at gun shows, and force it through a dealer like Cali. does.......A serious blow to gun rights since it equivocates to lifetime registration of a firearm regardless of who owns it.....It's also why I will almost never buy a new firearm or a used firearm from a dealer, The gov't doesn't need to know what's in my safe....Closing the loop hole would extend that hazard to all guns, not just ones purchased from a dealer...