Personal agents have been developed that assist user with information processing needs by generating, filtering, collecting, or transforming information. On the other hand internet stores are providing services customized by the needs and interests of individual customers. Such services can be viewed as "seller’s agents" whose goal is to push merchandise and/or services on to the users. This leads us to believe that there is a growing need for deploying "buyer’s agents" whose goal is to best serve the user’s interests. We propose several key functionalities of such buyer’s agents: informing consumers of complex interactions between specified preferences and prevailing market conditions, providing differential analysis for decision support, use of ontology to help the user reformulate queries.