The following are some of the more well-known and reputable online outlets selling potassium iodide as a thyroid-protective agent.
IOSAT is one of the key FDA-approved brands of potassium iodide, and Iherb offers the product at a good price, with fast delivery.
NukePills.com sells IOSAT brand potassium iodide pills for use during nuclear emergencies.
Rad-Guard sells IOSAT brand potassium iodide tablets.
Two Tigers sells Rad Block brand potassium iodide tablets.
Anbex sells IOSAT brand potassium iodide for radiation protection in a nuclear emergency.
KI4U provides Rad Block brand of potassium iodide, as well as extensive information on the drug. They also sell KI4U's own KIO3 brand of potassium iodide.