Walmart in Katy (west of Houston) is 3.74 for one gallon of 10%. That beats the new HD prices easily. Leslies 12.5% used to be 4.00 in a box of four for 15.99. Then they went to 16.99, then during the early months of pandemic panic, went to 19.99. So now I have Walmart 3.75 (for $4.68 adjusted to 12.5% equivalent) or HD at 4.33 ($5.42 at 12.5% equivalent) or Leslies at $5.00. I hate to say it, but considering the ease of handling at Leslies (drive up to the door, carry out a 4-pack in a convenient box with hand holds) for a little more than Walmart or a little less than HD--and without having to go in Walmart of HD.
Pinch a Penny has some kind of refill deal with a 2.5 gallon reusable container that you have to buy for about $10 to start. The guy I asked there about the strength was unsure but added, "I'm sure it's as strong as you can get." Really? Last quotes I got for a SWCG install were not that appealing, and now with pools under construction everywhere, it's probably worse.