The Koch’s are irrelevant.  They are just the easiest source of money. But it doesn’t take much money to run a think tank, so there are a lot of them. The libertarian spectrum is roughly aligned with the conservative,  Right Libertarian, Left Libertarian, and Anarchist spectrum, and most of us are associated with one or more of the Think Tanks that address the conservative – libertarian spectrum. 

They are (key players only):

CONSERVATIVE LIBERTARIAN

  1. The Heritage Foundation : conservative libertarians (focus on norms and the family)

MIDDLE (Classical Liberal Libertarian)

  1. Cato: Well connected, Republican Libertarians (focus on practical action to minimize government).
  2. The Future of Freedom Foundation   “Individual liberty, free markets, private property and limited government.” The FFF takes its libertarianism very seriously, so much so that even liberals may find themselves nodding while reading.
  3. The Heartland Institute  Moderate libertarianism, go to “PolicyBot”.

RADICAL (Anarcho Capitalist Libertarian)

  1. Mises Institute : Anarchic Libertarians (focus on eliminating the state )
  2. Property and Freedom Society: (Focus on small private governments similar to monarchies.)

OTHERS

  • American Enterprise Institute ( focus on entrepreneurship and economics)
  • Independent Institute    Aims to eliminate government influence and 5) interference in all aspects of life.
  • Cascade Policy Institute     Libertarian and oriented toward Oregon, there are broader issues under “Policy Areas”.
  • Institute for Policy Innovation   With the usual emphasis on “lower taxes, fewer regulations, and a smaller, less-intrusive government” pertaining to social security and healthcare, the IPI also addresses intellectual property and technological issues.
  • Lexington Institute    Libertarian views on defense, education, regulation, homeland security, immigration, Cuba and postal reform.

FULL LISTS
There are a lot of them and less than half are listed in wikipedia.

https://www.quora.com/What-are-the-key-differences-between-mainstream-libertarian-thought-and-the-positions-taken-by-Koch-sponsored-organizations