• Other estimates of Sanders' proposal have landed on roughly the same price tag.

Yes, but: It's still less expensive than what we're projected to spend now. If Mercatus' estimates are correct, Sanders' plan would cost about $2 trillion less, over 10 years, than the status quo.

The difference is where the money comes from. We spend a ton of money right now on health care — about $3.3 trillion in 2016, which comes out to more than $10,000 per person. That’s far more than any other industrialized nation.

• Those expenses are spread across taxes (to fund Medicare and Medicaid), premiums (from both individuals and employers), and out-of-pocket spending.

Between the lines: Countries with established single-payer systems spend a lot less than the U.S. on health care now, but Sanders' proposal is more generous than some of those systems. That puts it on the most expensive end of the spectrum.

• Mercatus assumes that Sanders' new federally run program would only pay doctors and hospitals Medicare rates (as his plan calls for). If a future Congress compromised with those powerful lobbies, as Congress often has in the past, the savings would diminish.