The Economics of Open Source
Jason Kau writes " is a working paper on the economics of open source software from the Nation Bureau of Economic Research entitled "The Simple Economics of Open Source". Focuses primarily on Apache, Perl, and Sendmail but mentions Linux, Debian, VA Linux, etc. It's a 40 page PDF document. Some background in Economics would probably be helpful."
Try
http://www.people.hbs.edu/jlerner/publications.
for the free download of the working paper.