Negotiation events in industrial procurement involving multiple, highly customisable goods pose serious challenges to buying agents when trying to determine the best set of providing agents? offers. Typically, a buying agent?s decision involves a large variety of constraints that may involve attributes of a very same item as well as attributes of multiple items. In this paper we describe iBundler, an agent-aware negotiation service to solve the winner determination problem considering buyers? and providers? constraints and preferences.