Information Systems researchers continue to develop Web services hoping that, in a near future, these services will be widely offered in the e-marketplace, using a Web-based protocol that is universally adopted for posting, locating and invoking available services. Posting services does not, however, necessarily lead to market transactions, and a number of brokering activities are needed to facilitate trade. These include, but are not limited to, service discovery and ranking, price negotiation and contract preparation. We propose a set of Web services that support the process of negotiation and bargaining to facilitate the matching of supply and demand of Web services. As a market broker, these web services would help (a) discover the supply/demand of web services in e-marketplaces; (b) find the most appropriate available service for a specific request; (c) facilitate services be modified if needed to satisfy user's needs; (d) arbitrate the pricing mechanism with the recourse to bargaining whenever necessary; and (e) generate a contract. As a proof of concept, we illustrate the potential use of Web services for negotiation and bargaining in e-procurement.