Statute establishes procedures for the development, calculation, and communication of rates promulgated by the Department for the purchase of services for persons with a developmental disability and persons with mental illness. Statute requires that rates be equitable, understandable, and established through an open and public process. The rate-setting policy should stimulate the development of cost-effective, clinically appropriate, community-based residential, and other support services for recipients according to an annual statement of purchase care goals and objectives.