Vernal, everything you have mentioned is magnesium chloride... we are simply discussing the relative purity of each source. There are many different grades of Nigari, just as well as there are different grades of dead sea salt. I think it also makes a difference how you plan on using the product? If you are bathing in it, then the purity of dead sea salts or nigari may not be as much of an issue. Although, the folks at Ancient Minerals do produce a 32 pound size for about 150 bucks, which isn't that bad in my opinion. Dead Sea salts and some good nigari will run you perhaps 25% less. Another trick you can do with any of the above is to leave your tub full for a couple days and just warm it up with some boiling water off the stove. If you are talking about using the product orally and in eye washes as I have actually heard some professionals recommending, then the Ancient Minerals magnesium oil is what I would stick to. Good luck