http://www.girlscouts.org/en/faq/faq/social-issues.html
Every Girl Scout and Girl Guide organization is a member of the World Association of Girl Guides and Girl Scouts—and each Member Organization, including Girl Scouts of the USA, pays dues. WAGGGS operates in much the same way as the United Nations: Each Member Organization pays dues based on the size of its membership and the per capita income of the country in which the organization resides.
I wonder which country provides most of the funding?
Well there are 10 million members and 2.5 million of them are American
So do the math
Membership is $15 a year and that is dues to both GSUSA and WAGGGS