In this paper, we present one such commerce middleware component -- an Auction Manager designed to simplify and automate both the creation of new markets and the matching of users to existing markets. The Auction Manager determines which markets are appropriate for a given buyer or seller using market-specific inference rules applied to the current market offerings. We also show how these same inference rules can be used by the Auction Manager to automatically compose and decompose market offerings to respond to changing conditions within the marketplace. Finally, we describe how the Auction Manager provides a focal point for expressing policy decisions such as how much to charge for starting and running auctions, as well as who and when to charge.