A collaborative bargaining system receives expressions of interest from potential buyers of an item. The collaborative bargaining system receives bids from sellers of the item. Each bid consists of a price per item based on a minimum quantity of items. A time limited exclusive opportunity is awarded to one seller of the item to obtain from the interest group a commitment to buy the minimum quantity of items at the price per item as bid by the one seller. Sales of the item are closed when the interest group commits to buy the minimum quantity of items.