I wouldn't characterize it as inexpensive. I called it fiscally responsible because it's much less expensive than what we currently pay and we will get actual care and not just insurance. 
As for CA, it would cost more than their entire current budget. However, they have 39 million people in that state. One study of a potential way for them to pay for it pegged the price at about $9.5k/person per yr. 
That's still less than the current average spent on insurance, even though it is more than their current budget. 
We need to look at what we get for the money, as a society. Not so much how it compares to the current budget, since the current results are unacceptable for so many and unsustainable for our future. The benefits to society across so many levels beyond healthcare can no longer be denied.