I was not saying the person is scamming people because the price is reached $900, I was just wondering if "someone" was bidding the price up on behalf of the seller like others have suggested. I find it hard to believe that many bidders are just missing the GPs that are selling for $200-350 less than that one.
"Shill bidding" is a possibility, but it's a risk for the seller, because if one if his "shills" pushes it too far and ends up being the winning bidder, then the seller has just wasted his time. Plus, wouldn't the seller still be responsible for the listing fees? (I don't know if GB charges fees to the seller, but I imagine they do).