Same thing can happen on eBay.

I recently had an item listed with a Buy It Now price with the Make an Offer option also in play

Someone made an offer of about $65 less than than my BIN and I countered with an offer of about $35 less. If the guy takes that offer, the auction is over with him as the winner.

In the meantime, someone hits the Buy It Now and ends the auction. Scooped.