Grays will be calling the highest bidder and trying to screw more money out of them, effectively negotiating a "best deal" for the seller.
If the buyer agrees to the price set by the owner, or if the owner agrees to the highest "behind the scenes" offer by the buyer, the aircraft is sold, and Grays will get their chop. But these deals are never posted online, on the auction site.
It appears to me the buyers highest offer is not far short of the owners reserve, and perhaps a deal has been done. If no deal comes out of the negotiations, the item will often be listed again - usually at the reserve price as a starting bid.
I bought a food van from Grays on behalf of a family member, it had been through several auctions over several months, and always failed to make the reserve. It was a really nice van, near new, and probably worth around $50K.
I'd estimate the sellers probably paid $70K for it new, just a couple of years before. They were baling out of the mobile food van business, and it was complete with everything needed to start selling food, even down to boxes of plastic containers.
The previous bidders always stopped around about $24K. Grays listed it at a starting bid of $25K, and I put one bid on it (the only bid), and I was quite surprised when it was sold to me instantly. It was a real bargain, and the family member was wrapped in it. Sometimes there's only one buyer for the item you're trying to quit, and if you find them, you have to take what they offer.