It might be something in between that and the current American price. That would mean more money from foreign customers who stick, but less from American customers and nothing from foreigners who drop out. The bottom line might well be not a bargain but a drug that never gets developed at all. It's not because we're so generous and forward-thinking. It's because we have no leverage.
Leverage comes from negotiating as a group, which means giving up some rights to individual choice.
The Hillary experience made any suggestion along those lines political anathema. Leverage ultimately means being willing to walk. In this context, it would mean convincing the drug companies we would actually rather see some new wonder drug go undeveloped than pay what they're asking. I'm not sure it's necessary for the richest nation in the history of the world to play poker like this with its own lives and health. I'm absolutely sure we're not capable of it.