Typical health insurance runs about $2000/year for an individual. If you buy with a large group of people, the price will fall drastically. At my university all students, faculty, and staff can get health insurance at $500/year. I bet all universities have some sort of group plan like that. However, since I am a grad student, I get my health insurance paid for me by the university - I'd say about 50% of universities will pay for grad student health insurance.
For me, that doesn't cover dental or eyes. So my total cost is $100/year since I pay for those out of pocket. Your university plan may include them.
Are you still under 25 years old? If so your parents health insurance will probably still cover you even though you are a grad student.