While the number of electronic marketplaces has increased on the Internet, tools to help buyers in participating in these marketplaces (heterogeneous marketplaces) are lacking. As part of the European Union funded eBroker project on electronic marketplaces, we attempt to address this problem by developing tools that help buyers in trading in these electronic marketplaces. This paper addresses the following issues: problems buyers face when trading in heterogeneous marketplaces, sources of problems, and how to solve them