I don't live in the US but asked some colleagues in New York how much it would be for a self employed person with a family (of 4 as an example) and they told me around $20K/year. Your figures are very far off that, what gives, is it because there are so many options it's like choosing anywhere from a low end to a high end restaurant?
In essence, yes. GP quoted figures for a high-deductible health plan. The premiums are low because the deductible is high - you would have to pay thousands of dollars of any medical bill out-of-pocket before the insurance plan would start to cover expenses. Low-deductible plans (insurance covers practically all of any bill) are available, but the premiums are substantially higher, especially for higher-income people ineligible for government subsidies.
GP figures might exist in NY if it's a) a very low-income situation or b) a generous employer that covers most of the cost, and the employee's contribution is minimal. Neither applies to a typical self-employed family.
It fully depends on your income. The poster above said "with subsidies".
With a family of 4, you would get some for of subsidy all the way up to about $100k mAGI.
One important thing to note about that modified adjusted gross income number is there are a few things you can control about it. Like contributions to retirement accounts and college funds will reduce your agi.