California is a big state with a nearly $200 billion annual budget. It's also a liberal state, where some lawmakers want to create a universal single-payer healthcare system.
Today, they got an estimate from the state's legislative analysts of how much such a system would cost: $400 billion per year.
This is not quite as big as total national spending on Medicaid (about $553 billion last year), or the Pentagon's budget for defending all 50 states and much of the world besides (about $585 billion), but it's on the same order of magnitude. And it's a whole heck of a lot more money than exists in California's state budget currently.
Granted, not all of the money for CaliforniCare would have to be produced from nothing. If you take all of the money that California and its municipalities currently spend (some with federal help) on Medicaid and healthcare and public health and redirect everything to this new system, that leaves you a mere $200 billion short, or more than 100 percent of the state budget.
If you then turn around and increase taxes on all the individuals and businesses whom your plan aims to relieve of the financial burdens of healthcare, you could conceivably get another $100 billion to $150 billion without making them spend more money on aggregate (although one can imagine this would not be easy to redistribute fairly, and there will be some big losers in the process).
So in the end, the plan would create an estimated annual shortfall of merely $50 billion to $100 billion, or between 25 and 50 percent of the current budget. That's...well, that sounds like a great way to get people to move to Texas.