U.S. jellies, what experience do you have with ordering drugs via the mail from Canada?

My husband has a prescription drug that he needs to take in its name brand form. (The generic versions leave him unable to be more than 20 steps from a bathroom.) Most insurance companies have stopped covering it because of the cost. A 90 day supply now costs about $20,000. His doctor switched him to something else, but it’s not working.

The drug is available in Canada for $400 for a 90 day supply.

Any guidance is greatly appreciated.