My sorority has insurance, it was difficult to find and most insurance companies don't insure fraternities and sororities and the ones that do were extremely expensive since they are for bigger Panhel and IFC groups. We had to do a lot of research and put a lot of effort into securing a reasonable agent.
I'll be honest it is a lot of money and if you don't want to raise dues then do fundraisers. We did not raise dues but fundraised and relied on family and friends to contribute. It was worth it, we have liability insurance and all our members are covered. This looks good when we speak with campus administrators about our organization and gives us a sense of security.
Hope this helps.