I thought a bit more about the tax issue and hauled out a couple of IRS publications and you're right.
When we do the auction for the school, we are careful to list the retail price on items where it can be established, that bottle of wine for example. It's listed in the auction program so that bidders know upfront what the value of the item is. Why would anyone bit over that price when they could stop at the grocery store on the way home from the auction and buy the same bottle for the retail price? Answer: because they want to make a donation to our school. And that's what makes the additional amount tax-deductible. The $35 bottle of wine is just a way of having fun with the donation.
When we can't fix the value of an item, having our principal come and read a bedtime story for your child, then the value of the item is what "the market" fixed it at via the auction and there is no donation.
Some items, though, are grey. Take that chair I mentioned. You could buy the same chair, unpainted, for less than $100. Wby did this one go for $1600? Was it because the buyer want to make a donation to our school, or was it because the students had finger painted on the chair giving it a special value that could only be determined by the auction? In the past, the IRS has been very generous to us and to other chariites allowing us to assert that it is just a $100 chair and, therefore, the amount paid above $100 is a tax-deductible donation.
Keep in mind that the IRS has its public image to be concerned about. They like "IRS clamps down on Billion-dollar corporate fraud." The don't like, "IRS denies $1500 donation to church school." The same thing could have worked here. If the makers of these knives had stated, "I sell similar knives for $X," as long as the amount was at all reasonable, the IRS would not want to go to bat and risk a headline of "IRS Dickers over donation to 9/11 Firefighers."
But, by declaring in writting that these knives have a special value that can only be fixed by the auction, I suspect they blew that opportunity and the buyer is simply going to have to buy the knives and forget about any tax benefit.
I also agree with you on the price. I've seen many cases on eBay where a seller has listed an item with a high minimum bid, got no bids, relisted it at the same minimum again and again and again with the same result, then finally listed it with no or a considerably lower minimum, and ended up closing the auction above their initial minimum bid.