[drcy]

Some people negotiate to the end of time, and some people negotiate without the intention of buying. An ongoing negotiation means the person hasn't even agreed that he will ever purchase it. I've chosen not to sell a card to someone simply because I was tired of their endless counter offers. "Sorry, the card's no long for sale."

The seller did nothing wrong.

The wrong would be if the seller agreed to sell it at a lower negotiated price then backed out.

If there's a sell price and you're trying to get it lower, you have to realize that you're taking the risk that someone will come along and take it at the full price. The BIN example was a good example.

Also, as someone pointed out, if it's not an auction, a seller can sell a card to whomever he wants at any price at any time.