Nothing wrong with this at all. I've had offers to purchase off ebay, which is better for the seller anyways.
As long it's compliance with eBay's rules and regulations. (sarcastic end) Actually, there are no rule or regulation regarding to ask seller at anytime. Maybe some seller may find it offend, but very small number of them would be offended. As many others stated, we often contact seller to see if they can negotiate on price. One advice on contact sellers, let auction run for at least three or four days before contact seller. That way, you can open dialogue with seller that evidence showed no one has make offer on his price and you can jump in to make an offer. Of course, low balling offers will get you nowhere and not so friendly toward sellers. Remember, sellers are human beings just like buyers.
There is also the opposite scenario, where a seller encounters non payment, contacts you as the second highest bidder and asks you if you want the item at your absolute max price. If bidding the absolute max price in hopes of getting it much cheaper, the response is usually no. Many buyers don't trust those second chance offers, not being certain who the non-paying winner actually was. They prefer to try their luck on a relisting.
I used to do this all the time, years ago. Ebay is such a different world today. I may actually know the seller from the forums. Not sure. He listed it again and I made an offer. Probably should have made it before he listed it again. I'm thinking I might get a PM on one of the forums. Thanks again for all the great information from the folks here. I'll let you know how it all turns out.
A while back there were a few Brazilian coins I really wanted being sold by a guy in Switzerland. I think they were listed for $10 and I had them on my watch list intending to bid at the last minute to avoid a bidding war. Well, I forgot to bid and it ended without any bids. I contacted him and said I wanted to buy them, and he responded that he would sell them to me for $20. Somehow the price doubled. But since there seemed to be a language barrier and I still thought the price was decent, I agreed anyway. If he had relisted they may have gone for four times as much.
Yes, I agree with all. I send offers all the time. The ones that get me are the BINs and you offer 5% less and you get a instant "NO". Those sellers I don't go back and BIN for the item.