Here is part of their mission statement:
Americans for Prosperity (AFP) and Americans for Prosperity Foundation (AFP Foundation) are committed to educating citizens about economic policy and mobilizing those citizens as advocates in the public policy process. AFP is an organization of grassroots leaders who engage citizens in the name of limited government and free markets on the local, state and federal levels. The grassroots members of AFP advocate for public policies that champion the principles of entrepreneurship and fiscal and regulatory restraint.
I believe that membership is free but donations are welcome. You can sign up here. A website for the Georgia chapter will be coming soon.