Prices of competitors. E.g., a seller of an item may automatically detect the lowest price currently offered for that item, and suggest a price within $1 of that price.[1][2][3][4]
Personal information of the currently active buyer, such as her or his demographics and her or his interest in the product. If the seller detects that you are about to buy, your price goes up.[5]
Business information of the seller, such as the expected date in which he or she is going to receive new stocks, or her or his target selling velocity in units per day.[6]