I would think it's worth pretty close to the $800, or whatever the market will bear. I suspect the dealer is trying to rip ya off if its as you describe.
9mm should be a little more valuable than 45, IMO, because their were fewer made, but that's my subjective guess.
I would market it thru this website. I have used it and it's a great resource! You can sell it in-state (depending on your local laws) without an FFL, and you as owner can ship it to a FFL for an out of state sale if that is required by the receiver's state laws.
Get a cashier's check or postal money order before you ship. YMMV HTH
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Be mentally deliberate but muscularly fast. Aim for just above the belt buckle Wyatt Earp
"It is error alone that needs government support; truth can stand by itself." Tom Jefferson
If you have to shoot a man, shoot him in the guts, it may not kill him... sometimes they die slow, but it'll paralyze his brain and arm and the fight is all but over Wild Bill Hickok
Remember: When you attempt to rationalize two inconsistent positions, you risk drowning as your own sewage backs up.
45 ACP: Give 'em a new navel! BigG