Acquired software products from suppliers are being increasing tremendously because of insufficiency of resources and capable employees. To manage and monitor the product acquisition process effectively according to a signed contract with a supplier, an organization has to define the standard of workflow, deliverable products in each step and staff roles and responsibilities, etc. Thus, there is a need to incorporate these diversified processes into a single process model that could helps to reach the software product acquisition goal. CMMI defines Supplier Agreement Management process area (SAM) that relates to product acquisition but it does not describe how the organization should do to achieve its expectation. This research presents a business workflow process model for SAM process area of CMMI: capability level 2. It consists of three layers: contextual layer, elaboration layer, and definition layer. A software tool called Supplier Agreement Management Tool (SAMT) is also developed to help integrate the details of our approach and can be used for the proposed process model.