There is not one insulin. This is a lot more complicated than that.

Due to recent developments, there are now start ups that claim they will be selling insulin for 25-50 dollars per vial. Whether that happens, as with the California production, we will have to wait and see.
Of course, the government can always select one specific drug and provide it at below the cost to produce. The trick is affordable healthcare in every category in a way that doesn’t bankrupt the government.
And this is not a universal problem with people having trouble affording insulin. If you are on Medicare D or have decent health insurance, you are not overwhelmed. It’s not really clear which people under which circumstances need help. Why would you be developing a new state paid insulin factory for the benefit of those currently paying about $13 a month for insulin?