Since you're dancing around the point so much, I'll be more direct. Here are specific questions that I suspect Coinbase also had:

What vitamin is unavailable in the US but available internationally?

Is said vitamin legal to import to the US?

Why does the vendor not take anything but Bitcoin?

Why can't you wait a couple weeks to get it?

Where were you getting it previously without Bitcoin, given that it's so critical you can't go without?