From the Chicago School of Economics, there is David Friedman with "The machinery of freedom". [1]

A large part of the Austrian school of economics is also ancap. A great overview of the insights today can be found in "Libertarianism today" by Jacob Huebert. [2]

[1] www.voluntaryistpunk.com/ebooks/The_Machinery_of_Freedom_.pdf [2] http://mises.org/store/Libertarianism-Today-P10394.aspx

Edit: You talked about money in a free market. For that topic I recommend "What has government done to our money?" by Murray Rothbard. [3]

[3] mises.org/books/whathasgovernmentdone.pdf