The heart of the question comes back to what you actually want to fix. I don't know you. A lot of people would just like to pay less for the thing they currently receive which is a nice sentiment but often hard to resolve. A large set of those people are actually upset because they have been led to believe they are paying a lot more than other people for the same thing, which I do not believe to be actually true.
One solution that does seem palatable to a lot of people, not me, but a lot, is "I would like like to appear to pay less for what I receive while the real costs are hidden and subsidized in a way that is much less visible to me". While popular this view is not popular enough to adopt legislation to that effect.
In practical terms detailed policy legislation that makes losers out of a lot of low value transactional middle men would see some very meaningful across the board cost reductions, probably 7-10% (500 billion or more). Top of that list would be intelligent standardization and regulation of transactional medical billing process. This would/could look a little bit like how we regulate banking between financial institutions. Very sexy I know.