Some responses--
I already save that ton of money by not using fabric softener at all.
I never buy detergent at the dollar stores because they are not good buys in my book.
I bought Costco's Kirkland detergent one time but it would not dissolve in our cold water in winter. Our water is from a partly frozen river and then goes to some open reservoirs, so it is cold in winter!) In summer, perhaps it would work.
We do not have CVS here, so there will be no detergent freebies from there. What is WAG? Is that Walgreens? Walgreens here does not reliably stock the items on which they are advertising rebates or really good sales.
Well, I think my plan is I will buy another box of Kirkland's next time I'm at Costco. For summer cold water washing and all hot water washing, I think it should work. Other than that I will mostly just stick with my favorites and continue to watch for sales on them.
Does no one buy detergent from an industrial supply such as sells to commercial laundries, hospitals, and such? I thought maybe someone here would have a novel way to get good detergent at a great price.