I'd look at pcgs and the coin facts to see the population and current prices that a coin like this fetched.
You can find a coin like this in MS for about 1/10th of that, in MS-63 to MS-65.
Great Collections start coins low, but it is a matter of time before they go through the roof.
I HIGHLY suggest reading the auction rules. SOME of the auction houses allow the owner of the coin, or the staff of the auction house to bid on coins. If the owner of the coin wins the auction, he simply pays the auction fee. Its stupid on some of the ways they do insider bidding to ramp up the cost and make more commissions. I know TELETRADE has done that in the past but I don't know if GC does it or not.