I think you're wrong here.
Adding an extra minute after a higher bid at the end of an auction would give all those people who were willing to spend an extra dollar or two ('don't lose it for a buck, folks') a moment to think about it and bid again.
It would ruin the 'snipe' market, but it would drive up the final price in many cases, which is what both the seller AND Ebay would like.
I believe it would raise final prices, not lower them.
Kerry