The Web repositories are exposed in form of a huge amount of heterogeneous information sources. The information is overwhelming the users. Besides the target information itself, the changes upon the previously released information are significant and worth being notified to those who perceived the out of date information as soon as possible. The changes made in Web repositories occur at unpredictable rates. Unfortunately, stock type information source has no means to inform its prospective users about the changes. While the stock type information source occupies a large percentage of sources on the Web, it is necessary to have a system that monitors changes on the Web, and provides comprehensive presentation to the prospective users. In this paper, we proposes a mechanism that provides change monitoring and presentation service for a large group of users by coalition among service agents. The service agents keep improving the overall utilization factor by several schemes based on the decision made by game analysis. We apply a cost model to the service mechanism in order to study the cooperative behavior of the service agents. The reduction of cost is designed to comply with the level of cooperation among service agents. This paper presents a paradigm for the service and the formation of cooperative behavior of the agents in the community.