I have made repeated offers to buy as well as minor counter-offers to folks posting, in accordance with their wishes, via e-mail to the correct e-mail address with all of my contact information. The last 2 times, I offered a bit less than the asking price in a good faith attempt at negotiation ($425 vs. $450 asking) with no reply. I check to find that the item was sold a few hours later. Meanwhile, I've been watching my e-mail while out on the town, in the event that the seller has responded, and it's only fair to not keep them waiting. I personally would either reply that the I was too late, the item has been sold or that there is no room to negotiate (where I would most likely immediately agree to the asking price, otherwise I wouldn't have wasted the OPs time.) The times I've sold, I have responded to every e-mail out of respect as I expect most hams to either purchase, negotiate or ask questions. I think the courtesy of a reply is the right thing to do. That's just my opinion, I could be wrong.