I have about 14K rounds to sell and was going to list it on GB but I called the one gun shop we have here and he suggested I put an ad on his bulletin board. He said people check it every day and I'll probably have it all sold within a month even at GB prices. I'm giving it a shot. He wants nothing for use of his board.
It might be worth your time to check your local pawn shop and gun dealer bulletin boards?
Put it on Armslist too. It's like Craigslist, but for guns and ammo and stuff. Simple, fast, no fees; put it in a local section.