Being in the medical field, I can tell you this much. You get what you pay for in some respect. If you sign up for a crappy HMO, you will be forced to select from a list of providers that subscribe to this HMO. Now think about that. You're paying a really low premium because the HMO pays the doctors really low fees, so what KIND of doctor is going to accept it? Probably not good ones on the average. However, if you are pretty healthy and just want insurance for that "just in case" and don't really plan on using it, then a healthy young man non-smoker can get health for around $120 month on an HMO. If you think you might use it, get a PPO or indemnity that gives you freedom to choose outside the list of providers. The fees and copays are higher but worth it.
That kind of thing is very regional. Check with your local Chamber of Commerce if you're getting it through work or setting it up for your business. They might have some contacts or advice for you. Your accountant might also be helpful, they deal with a lot of companies so s/he might be a good resource.