Recently in the UK Buzzsaw has become costed by Users rather than storage - Buzzsaw allows you to cap storage by having the limits tab in Site Admin is there now plans to add a limit per project of users added so that individual projects are stopped from over using users?
I believe # of users has always been part of your service agreement, i.e. each Buzzsaw subscription would allow for a maximum number of users on the site, and the site administrator would need to work with his or her project administrators to manage them effectively.
I don't believe there are immediate plans to allow user limits on projects, but that is a great suggestion that I will add to our suggestion list.
In the meantime, a few areas that may assist - 1) the Site Administration > Statistics tab allows you to see member count across all projects, so you can see which projects are using the most number of users; 2) the Site Administration > Members tab now allows you to see Inactive members so you can restrict usage to just those who will be logging in; and 3) the Site Administration > Security tab has an option for automatically disabling members after a certain period of inactiivity.