You can get those kits everywhere you can buy the gelcaps but '00' is perhaps too large.. Too early to tell about the nausea.

I had a tough time finding pure kcl as well but I bought a big 50 lb bag of kcl pellets for water softening from my local hardware store. Looked up the company and found the analysis to be 100 percent kcl. Came in chunks of all different sizes like crystals. Bag was $30 so I'm set forever haha. Just difficult to measure but a mort and pestle solves that.