Walmart in New Hartford, NY has "Pool Strength Chlorine" at $2.50 for 10% !!! I believe it's a full gallon as well (don't have bottle convenient to me at the moment). That bests their house bleach at 121oz of 8.25% for $2.75 I think (might even be higher).
First time running it, so I hope it's fresh. I've tried Aldi's Bleach vs Walmart Bleach and the pool never seemed to hold the FC as well (I could be dreaming this).
I just happened to see this the other day as well, same store. I was over there to get CYA and luckily happened to turn around. Haven't noticed any issues since going to this from GV brand 8.25%.