Abstract: An online buying group (referred to herein as a “co-op”) is formed for the specific purpose of purchasing a particular product at (102) by defining a start time, end time, critical mass, any minimum number of units offered, any maximum number of units offered, starting price and product cost curve. As data is gathered from buyers, by means of their making binding purchase offers, the co-op is modified at (108) using a pricing tool, so as to take into account for this market data in the definition of the price curve. A buyer chooses a product co-op of interest at (114). The buyer is presented with the following essential co-op information: current price, closing time, next price level (as defined by a price curve visibility window and the price curve) sufficient to entice the buyer to make an offer.