Fifty percent is far too low. It should be 75% to 80% for starters beginning with all federal law enforcement bodies. Then we start eliminating whole useless government departments and agencies like the EPA, HHS, Dept of Education, DHS, HUD, Dept of Labor, Dept of Commerce, for starters.
Here is the complete list of all U.S. government departments and agencies for all three branches: http://www.usa.gov/Agencies.shtml. This is a target rich environment.
Yeh I was just being conservative. Your list of agencies mirrors my list.
That's a stupid list, here's a better one — agencies commissioned or otherwise authorized by the Constitution: