Thank you guys for all your input. Here is the research I did based on what I read here and on my own:
Places to buy chlorine in Houston (I am in Southwest part of Houston, so driving up to Spring to Napco is not an option for me)
1. Home Depot--HDX Chlorinating Liquid 3x1 gal 10% for $9.98. The question now is which HD has the fresh stuff...
2. HEB--HEB Bravo Concentrated Regular Bleach 121 oz 8.25% for $2.67
3. Leslie's Pool Supplies--Chlorinating Liquid 4x1 gal 12% for $17. You have to ask, they have it in the back of the store. I don't know how fresh it is.
Walmart and Target have slightly more expensive bleach (Pool Essentials [if you can find it] in WM, Up & Up in Target).
I also checked Dollar Tree, Dollar General, King Dollar, Family Dollar, and 99 Cent Store. Dollar General and Family Dollar are the only ones that had good concentration bleach (their store brand), but was still more expensive than the three top options I listed. I saw bleach on sale at Dollar General for the price of the Home Depot's, but it was very old.
Using the calculator from the original post in this thread, I found that the cheapest chlorine price around where I live is 26 cents/oz. Please share if you found lower price in Houston (southwest part).