[drcy]

The general rule is the card is sold to the first person who makes an acceptable offer. I don't know why a seller would continue to advertise and send photos for a card that has been sold. A common problem for sellers is waiting around for querying or requesting potential buyers to make (or never make) offers and return (or never return) messages. Many people sell with a figurative (or, on eBay, real) "Buy it Now" button in the sale's description: First person to press the button, or email "I'll buy it", gets it.

Certainly, a seller can and some may say "Someone else emailed about the card first and I'll give him a little bit to respond," but it isn't a requirement

Though I understand and appreciate the OP's sentiments.