Of course, being a graduate student who had to miss out on Greek life as an undergrad, I would be interested in something like that.
Is the sorority your suggesting ONLY for grad students? With that said, I would be concerned about not having many members. After all, grad students are more like to have jobs, spouses, kids, thesis papers, research etc and not want to be involved with a sorority. Maybe you could start a new sorority which accepts both grad and undergrad?
......Kelly