Same conclusion as above with example, and not to overemphasize the point on "honor," but as a private seller I once recently listed on the Internet at a fixed price an all-original 1911 Colt US Military (dated 1917) w/ original two-tone magazine and holster dated to 1917, that I'd bought fifteen years ago for a song from a little old lady from Pasadena CA (no kidding). I knew I did something wrong when within the first 30 minutes I had over 20 Emails in my Inbox on that gun. I of course sold it to the first taker and still made a profit but never again would I list something without checking its recent market value (I sold it all for $800).
On the flip side, as a buyer, on Thanksgiving early morning two years ago i checked a full-auto Internet sales site and some private seller at 7:30AM listed an HK MP5 sear gun for $12,250. Mind you, these went for no less than around $16,000 at the time and I emailed the seller with a firm "I'll Buy It." Obviously, nobody else was watching the sales site at that hour because he very quickly agreed via return Email to sell to me and asked me to call him. I called and we discussed and we closed the deal, or so i thought. He said he was going to Email me his payment address in a few hours after having to run an errand. I was so excited I awoke my wife and told her that at worst if we wished to sell the darned contraption that we made a couple $$thou that morning ! However, correction; i never got another Email from him. The seller delisted/marked the item sold by the end of the day. I called him that evening and he answered that someone offerred him more for it and so he took the other offer. I gave him a piece of my mind.
Buyers should commit to a purchase when they offer a figure and it's accepted; Sellers should commit to a purchase when someone accepts their price. Anything varying from this is without honor and a deceit.