It is well known that groups such as Americans for Prosperity (a rather Orwellian name as they are for the prosperity of only a very select few) are funded by the Koch brothers.
From Wikipedia,
with the original sources cited:
Americans for Prosperity was founded in 2004 when Citizens for a Sound Economy (CSE) split into FreedomWorks and the Americans for Prosperity Foundation (formerly the Citizens for a Sound Economy Foundation). Dick Armey, who had become chair of CSE in 2003 after retiring from Congress,[7] remained chairman of FreedomWorks, while David H. Koch remained chairman of the AFP Foundation. Like CSE, AFP was founded with the support of David H. Koch and Charles Koch, both of Koch Industries.[8][9][10]
sources:
7. "Dick Armey to lead Citizens for a Sound Economy". January 8, 2003.
8. Zernike, Kate (October 19, 2010). "Secretive Republican Donors Are Planning Ahead". New York Times.
9. Mayer, Jane (2009-01-07). "The billionaire Koch brothers' war against Obama". The New Yorker. Archived from the original on 15 October 2010. Retrieved 2010-10-21.
10. Overby, Peter (February 19, 2010). "Who's Raising Money For Tea Party Movement?". "David Koch has directly taken credit for founding Americans for Prosperity, saying, "Five years ago my brother Charles and I provided the funds to start the Americans for Prosperity.""