Buy it!s are subject to previously placed maxbids. So if a person placed a maxbid equal to the buy it price, before you hit the buy it button, that person will win.
When we introduced the Buy It feature to our site, we had to make it work with our current bidding rules. Under our current rules, earlier bids always take precedence. In order for Buy It's to work with our system we needed to ensure that rule was respected.
There was two ways to do that. First, the Buy It feature would disappear after the first bid or, it would remain, but be subject to previously placed maxbids. Other systems remove the Buy It price after the first bid, but we felt that favors the sellers to much. It encourages the seller to place a high Buy It price and try and preasure a bidder to pay that price because they know the Buy It price will disappear after the first bid.
For that reason, we decided to have the Buy It price remain after the bidding. But to do that, we had to respect our rule of earlier bids take precedence. There is a notice directly below the Buy It button on each item page that says "Buy It! Subject to previously placed max bids" with a link to more information.
