Commission on Affordable Health Care Act of 2008 - Establishes in the legislative branch the Commission on Affordable Health Care to: (1) conduct a comprehensive study of potential models for a health care system to provide affordable and quality health care to all U.S. citizens; and (2) make recommendations for implementing such a system. Requires the Commission to report to Congress on the study and include a legislative proposal that provides for a health care system based on the recommendations of the Commission. Provides for expedited congressional consideration of such a proposal.