Think Tanks are excellent sources of in depth reports on policy topics. The Harvard Kennedy School has a think tank search engine to locate reports only from think tanks.If you can't tell which Think Tank might cover your topic, try Advanced Google Search. To sort out the viewpoint of Think Tanks try the New York Times list. Journal articles often refer to good Think Tank reports.
Tips for searching Google Advanced mode:
Example of a search for the topic of state funding for universities:
All these words: report university state funding
One or more of these words: institute or center
Vanderbilt University
Public Policy Issues & Groups (Vanderbilt University)
ProPublica: Journalism in the Public Interest
Consumer Watch Groups may collect valuable information surrounding policy issues. Remember to search these out.