FYI-Here is what I did to make sure

My recipe:
1c Borax
1cWashing Soda (just recently available in my Wall-Mart)
1 bar soap grated
Use 1 Tbsp per load

Sometimes I use more-hey, we farm.  But I would use more of the store bought stuff in those cases too.  Now, a little background.  When I go to the store, I use the calculator on my phone and actually divide price by uses, and NEVER pay attention to the little store labels that tell how much per ounce, etc.  I do this for coke, TP, food, EVERYTHING.  You’d be surprised what the better deal is.  So, I’m using the cheapest laundry detergent at the store that I’m willing to use (some brands will fade or eat your clothes.  I don’t use those)

I have a digital scale, a chemistry background, and a soap making background.  I make my own soap, and tally up how much that cost me per bar.  I weigh how much a cup of this or that weighs and divide it into the total package weight, and that into the price.  Add it all up and divide by the total number of uses I get (using weight) and here is what I found:

Store bought: 19 cents a load
Homemade:  7 cents a load.

Three loads a week will save $18.72 per year.  Not a huge amount, but at least this way, you know it’s cheaper without having to guess.