I'm condsidering moving to the Valley as one of the options for myself as an entrepreneur I am concerned about the medical insurance. In my home country medicine is formally subsidized by the government and therefore I do not understand clearly how does the private medical insurance work.
I would be grateful if someone answered these questions:
Before you move to the US, you could consider getting some travel/visitor medical insurance from your home country - would help bridge the gap until you get something better. Also, its cheap enough.
You can purchase individual health insurance, but this generally gets to be pretty expensive. One option is www.ehealthinsurance.com. Pricing would depend on a bunch of factors including age, any pre-existing health conditions, smoker/non-smoker etc.
You could also join freelancers union or similar group and purchase health insurance at group rates - http://www.freelancersunion.org/insurance/how.html. This might be your best bet.
Edit: Sorry, looks like Freelancer's Union offers medical insurance only in NY, and not in CA. Hopefully, there would be other similar groups that you could join...
First question - on what type visa are planing to come to US?
It's very hard to get individual insurance for non-resident. Usually all insurance company ask about your residence status when you apply for insurance and deny if you are non-resident.
Your monthly premium amount depends on many things - your age, health conditions, coverage you choose, deductible you are willing to pay. Generally for self-employers it makes sense to buy hight deductible plan with low monthly premiums.
Insurance companies in my experience don't ask about citizenship but do ask for a social security number to make it easy to differentiate you from other people. You can use your tax ID number in this field if you have one.
The big thing is that insurance doesn't pay for everything, so many times you are better off getting a "catastrophic" or "emergency" plan and simply paying physicians out of pocket. An annual physical can cost $200 or so, with another $80 or so for comprehensive labs. EDIT: versus similar cost per month for a pretty "meh" plan. A catastrophic plan will have a high deductible ($2000 or so), but low monthly cost, and will cover you if you get into a major accident, have cancer etc. No matter what, you can get emergency trauma care in the US without paying up-front, but the bills can be costly.
Getting travel insurance should be pretty easy, and will cover you for quite a while. If you have a credit card, the card company may offer it at a discount rate.