Abstract: A commerce system has a plurality of retailers offering products for sale. Product information associated with the products is collected and stored in a central database. A consumer uses a website to create a shopping list with weighted preferences for product attributes. An individualized discount is generated by a consumer service provider for products on the shopping list directed to the consumer. The shopping list with all products aggregated for one retailer is optimized based on the product information in the database, the weighted preferences for the product attributes, and the individualized discounts. The consumer uses the optimized shopping list to assist with purchasing decisions. An incremental profit can be determined based on an aggregation of the products on the optimized shopping list. Purchasing decisions within the commerce system are controlled by enabling the consumer to select the products for purchase from the retailer.