A sales portal system supports a plurality of buyer computers used by a corresponding plurality of buyers. The sales portal system supports a first seller's computer to support sales of a first plurality of products a second seller's computer to support sales of a second plurality of products. The sales portal accesses first product data from the first seller's computer and second product data from the second seller's computer and responds to a query received from one of the plurality of buyer computers by delivering selections from the associated first product data and the associated second product data. The sales portal manages a single sales transaction for a first product of a first seller and a second product of a second seller. The sales portal rates sellers. The sales portal apportions payment, fulfillment, delivery instructions, and other sales components to the first and second sellers.