Just had this brought to my attention by a peer starting to use BBB. Another handy tool to add to our arsenal.
I noticed Walmart went with 33% more concentrated (7.78%), but dropped the volume to 121floz for $2.98 (Indiana). That seemed expensive for some reason so I mentioned shopping around to above peer. He found this calc and I love it. Look out price gougers, I'm out for the best deal!
Bleach price calculator