I have always been provided SAS as part of my job, so I never really realized how much it cost. I’ve bought Stata before, and of course R . I recently found out how much a reasonable bundle of SAS modules along with base SAS costs per year per seat, at least under the GSA. 










Zero Inflated Models and Generalized Linear Mixed Models with R.
Zuur, Saveliev, Ieno (2012).