1. A computer-implemented method for selecting an optimal balance between direct cost and a number of suppliers comprising: soliciting bids from a plurality of suppliers for a plurality of lots; storing bid information from a plurality of suppliers for a plurality of lots in a database; and upon completion of bidding for the plurality of lots: determining using a computer a first optimal solution that includes an initial family of lot-supplier assignments; and: if the first optimal solution has the lowest cost value: performing multiple iterations of the following steps: decreasing the number of suppliers in the family to form a reduced family; determining a revised cost value for the reduced family; and generating a second solution having the decreased number of suppliers; and if the first optimal solution has the highest cost value: performing multiple iterations of the following steps: increasing the number of suppliers in the family to form an increased family; determining a revised cost value for the increased family; and generating a second solution having the increased number of suppliers.