Source?
If you’re familiar at all with how to cap it in capsules or create a liquid, this is more cost effective than a lot of the other solutions out there:
https://www.amazon.com/Potassium-Iodide-Purity-Crystals-grams/dp/B01JKJWXBK/
This is what I bought although I did not research how many, in this strength, would be necessary.
I ordered from Amazon.