If you don't get an answer to this I found someone that you can ask. I just watched a video on youtube and he was making Lugols using both the powdered forms of potassium. His channel is Herbsplusbeadworks a very cool canuck.

Hope this helps.

http://www.hometrainingtools.com/potassium-iodide-30-g/p/CH-KI/


You can also try ebay.