Family sponsorship is limited to parent, grandparents, and children. If your family in the US is any more removed than that, they can't sponsor you. The days of people bringing in aunts, uncles, and cousins are long gone.

If you have any pre-existing health conditions, you might not be able to get any private insurance at all. Obviously company coverage isn't an option for you, since you will be retired. Catastrophic coverage usually has really high deductibles per incident. So, if you break your ankle and need surgery and rehab, as I did in 1999, the insurance will only cover you after a certain level (my ankle, retail, cost $45,000, by the way). If you break an arm the next week, you have to satisfy a deductible again, until you reach another annual limit.

I'd figure on $700-$1500 per month if you can get coverage.