Ebay charges a listing fee, GB and AA do not. If you're not in a hurry there is no downside to listing a gun at top dollar and waiting for someone to bite. If the online auctions charged a listing fee based on the minimum opening bid I think you might see a change in this practice.

Last year I was considering a Remington M700 varmit rifle that was for sale locally. To get an idea of prices I searched completed auctions on GB for that particular model and found over 1000 auctions, only 2 sold.