"Pete S. - Nice try, but incorrect. You quote the User agreement "you are obligated to complete the transaction with the highest bidder upon the auction's completion". UPON THE AUCTION'S COMPLETION! Not "during the auction", but "upon completion"."

Well Mike If you end the auction early, its completed. The auction would be completed in any event.

"I've already shown you the pertinent parts of the User Agreement that instruct a seller exactly how to cancel all bids and "complete" an auction early, and shown you that getting a better price elsewhere is a valid reason for doing so."

No you haven't shown any such part of the user agreement. Here is a link to the user agreement it ain't in there . . .

http://pages.ebay.com/help/community/png-user.html

Show me one spot in the user agreement where it says a buyer may end a auction early for the reason you have stated.

I don't want the Seller to receive one penny less than the true value of his item, but I expect him tohonor the agreement . . . If I were the high bidder in this circumstance I would allow him to not complete the sale as long as it was understood that that was my decision not his.

When I post a bid, it stands and I honor it, I expect the Seller to do so as well. And Ebay might take the position that this is okay, but that is not what the user agreement says, and accordingly they are wrong if they refuse to enforce their user agreement.

If I were the seller right now, I would be looking for websites like this one so I could advertise the auction and bring bidders to it. It is not unheard of for auctions to start with low minimums and bring high bids. One friend of mine sold an item he had no idea the value of. He put a minimum bid of $99 and no reserve. The item was sold to the highest bidder for $25,200.00 http://members.ebay.com/aboutme/andylesley/ This seller did not help himself by telling his bidders that he wasn't going to honor the auction.

"If one of you club members came here and said they had put a big proxy bid on an item, and then discovered additional information that made the value of the object questionable, BEFORE THE AUCTION ENDED, would you all be telling him, "tough luck", and that he is under contract to complete the purchase?"
Absolutely that is what i would say, unless there was fraud or deception on the part of the Seller. And I have completed auctions where after posting a bid, I realized I had bid too much.