In case you don't know Lugol's was available at the three pharmacy's in Canada, where I inquired about it. One of them didn't have it in stock but can get 500 ml for $44.95 within a day (but not 100 ml.) It comes from Xenex Labs Inc in Coquitlin B.C., so no border crossing is needed.
They have a warehouse almost on the Canada/U.S. border in Washington state (driving distance - not likely mailing?) might be useful info for U.S. citizens living near there or in the state - at least a lead to follow for sources.