I'll bet you would make the same argument before the Pure Food and drug laws were passed. If people are sold poisonous food they can just stop buying it. If they are sold contaminated food they don't have to buy it. If your child would need a cancer fighting drug and it would cost the consumer $50.00 then would choose not to buy it if the manufacture decides to charge $1750.00 per pill and it required one pill per day. Libertarians are ridiculous.
Every pseudo intellectual libertarian would change their tune the instant their child came down with cancer and a drug company was charging "what it wanted."
There is always a rule of reason.