Personally, I think extending an auction will simply result in higher prices being paid for items. I think sniping (interesting term by the way, the connotation being something underhanded, unAmerican) is simply an e-auction phenomenon and a legitimate bidding tool. I've been beat and I've won, usually by bidding higher than I think the competition can guess what the bid increment will be. Personally, I probably won't participate in an auction that is extended at the last minute. The bidding pool is simply too large sometimes and what was a bargain turns into an expensive used part.
David Goerndt