Our lowes carries CYA in their (small) pool section. It is chlorox pool brand.
As Pool Tool mentioned, there are a couple of different strengths of MA. The "green" (low fume) stuff has a lower concentration (at same price). You can use it, but you have to adjust your pool math calculations for the needed amount. The "Jasco" brand carried by our lowes has a regular and "green" version, neither say the actual concentration on the label (I had to look it up online), so just be aware of what concentration you are getting.