Others are observing that the current prices are not currently anywhere near $100. That's completely unrelated to what I'm explaining.
I'd also point out that is a temporary fact, not a permanent fact. If, let's say, in two months the Coronavirus has mutated into a mark 2.0 and is sweeping through Illinois [1], getting insulin may become much more expensive due to all the measures needed to prevent spread of infection. If it becomes more than $100 worth of expensive, it's going to be difficult to distribute. There can be supply disruptions due to source contamination, whoknows what else. Even if today this seems like a generous cap, an inflexible cap can still be a problem tomorrow.
Of course, the last few years being what they are in online discourse, a large number of you will be inclined to read this as a defense of high prices, rather than what it actually is, which is an observation that price fixing has certain effects and that we don't know the future very reliably. Screwing around with insulin prices just because you can is evil and should be the grounds of a presumptive collusion, oligarchy, or monopoly investigation. But that doesn't mean that fixing the price is a good idea, or going to fix it. Personally I'd suggest getting a few state attorney's together and digging into why the price is so high, with an eye towards criminal charges or anti-trust action, would be much more effective. You might even find that "feels better" than mere price caps. Remove the incentives for people thinking they can get away with this sort of thing scott-free, rather than trying to treat the symptoms far down the pipeline from the root cause.
(Downvoters are invited to consider my replacement suggestion of criminal charges or significant antitrust action before deciding that I'm "defending" anything. This is a silly papering over of the problems by people who ought to have the power to do a lot more.)
[1]: A totally absurd, impossible scenario, of course. https://chicago.cbslocal.com/2020/01/24/first-case-of-corona...
