Earlier, I posted about marketing sleight of hand concerning Borax. I fear we may be facing the same dilemma with Muriatic Acid (MA). I have only checked this at Home Depot, since they are very close to home, but the Sales Associates strongly steered me to the "safe" MA in the paint aisles. I finally told them I had no interest in "being safe" and they reluctantly sent me out to the lawn and garden area for the real 20° Baume MA. These were boxed units, two gallons to a box, and it looked like they were not only old stock, but had endured a hard Norwegian winter.
For those unfamiliar with the "safe" variety, it is the normal 20° Baume MA, diluted to half-strength, with water.
Price for two gallon box of the 20° Baume MA? $12.98*
Price for two gallons of the half-strength stuff? $15.68
*Twice as much active ingredient for less money.... for a trek out to Lawn and Garden.... YMMV.