It is definitely a premium price for a premium product, and absolutely out of reach of many.
But that's the case for a great many custom and/or early adopter products.
It's not crazy. I regularly spend 80$+ for bras I don't like, and if I found one which worked with my wardrobe and truly fit comfortably, 350$ would not be a luxury purchase.
I know this might seem crazy, but some of us actually know women and can just ask them. My wife thinks $350 is insane for a bra. I have no doubt that you might gladly pay that, but it’s bizarre that you feel entitled to speak for half the global population.
edit: The point was that many of the people in the thread don't seem to understand the magnitude and pervasiveness of the problem. What people are prepared to do and pay to alleviate it is another matter entirely, but accordingly it is probably not well estimated if the issue is not well recognized.