Practical applications of multi-agent systems have acquired a growing relevance during last years. This kind of system is based on distributed artificial intelligence and they pay special attention to organizational concepts, This allows a more realistic design of artificial societies. In this paper, we are presenting a multi-agent system based on virtual organizations, which has been specially designed to model a Purchase Porter System aimed at helping clients of shops to transport their shopping. The system establish agreements to transport shopping to the more appropriated exists for the client. The system has been tested in a simulated environment and the initial results are promising.