One of the main issues in electronic commerce is the inclusion of the negotiation facilities commonly available in human client-vendor interaction in real world commerce. E-commerce negotiation processes have usually been modeled as self-interested multi-agent systems. In these systems buyers and sellers are represented by agents that have opposite demands and decide what to do on the flight, based on the available information. However, currently e-commerce systems, such as Kasbah and Magma [21], provide a small number of bilateral negotiation facilities. Fortunately, some general negotiation models could be at first applied to e-commerce domain. This is typically the case of Faratin’s model, which can be seen as an extension of Kasbah’s. In this paper, we propose an original bilateral agent negotiation model, which extends Faratin’s one. We introduce various facilities, such as alternative product suggestion, ultimatum generation, local contract agreements, etc. These facilities intend to grant users with a more flexible e-commerce environment. We present our model formalization, including the knowledge base that determines agent behavior. Some empirical validation is also presented to the case of computer purchase.