"I still think letting each state decide for itself has some merit in it."
Yes it does, apart from perhaps very small population States, but the people there could be given the opportunity to pay in to a nearby states system the same as if they were resident, and still take advantage, even if a bit of travel was involved ? maybe ? dunno. (maybe not , Social Care has to be considered kin the equation).
Obviously the ideal is for the whole Country to implement a proper system, then the well known money grabbers like Big Pharma would have to deal with a National buying Agency, with huge clout, an Agency who could buy from anywhere in the World.
But baby-steps could work.