buy it now price does not ever change physically persay. However in an auction if the current bid is already greater on an item than the buy it now the buy it now price will be that higher price thats just common sense. when you do bids the price of an ad is whatever the current bid is. If the current price ever gets past the buy it now price then your buy it now price goes up. You would not want to sell an item for less when you already have someone paying more money for it.