For someone selling an item on AudiogoN, there is no protocol that I can see declaring, "The seller must sell to the first firm offer at the asking price." Posting a classified does not carry with it the implications of a contract contained in the auction process, for either the buyer or the seller. Although "first come, first served" is indeed a common selling practice, and the one that I have used myself, other factors could enter into play: form of payment, geographical proximity, previous dealings with any of the respondents, perusal of feedback, quality of communication, the subsequent offer of a higher price, waiting to receive more responses, or just a personal perogative. To me, unless a seller actually renigs on their acceptance of an offer to sell a certain item for a certain amount and form of payment to a certain buyer, no foul. In the above case, however clumsily handled (and I presume the seller feels some sense of responsibility, otherwise he would not offer to sell the second cable), the parties at least agree that the seller made no such commitment to accept the buyer's offer. It's cases like these that prompt me to always include not only all of my personal info (as recommended above by myraj), but also a reiteration of all the specifics about the item description, price, payment form, and shipping arrangements when offering or accepting an offer to buy. In addition, when I am dealing with multiple offers to buy, I respond by telling each potential customer what their "place in line" is, but this is optional - a seller could just as legitimately respond by thanking the E-mailer for their offer and saying they'll get back in touch if the item proves still available. Like they say, discretion can be the better part of valor.
