I'm a former Freelancers Union member and though the plans are quite good in NY, they're not so hot outside of that area. The fact is they aren't a union and they aren't an insurance provider either. They're a membership organization that negotiates group eligibility and rates. There are other types of groups that do this as well, perhaps one where you live that has better relationships with your state's dominant HMOs.
I have private coverage purchased directly from my local Blue Cross/Blue Shield. I don't recommend this route, it's low-cost, but the coverage is full of loopholes. The advantage of a group like Freelancers Union is that the plans are vetted for "gotchas" and providers don't want to piss off thousands of customers who are semi-organized.
If you do go the retail route, be very careful. I'd liken the experience to buying electronics out of the back of a truck.