CMA is not a salt, but is synthetically produced and there for is a lot more expensive then natural materials which are mined/evaporated.
You can check out our site's CMA Information page...
http://gosalt.com/CMA_CALCIUM_MAGNES...ETATE_CMA.html
Just be aware there are many blends that contain mostly rock salt and very little CMA, but this is not what is required by the Walmart.
Give us a call at 800-221-5105 if you have any questions or for pricing.