I make this soap in our Food Processor. I use the shredding blade to shed the bars of soap, and the mix/chopping blade to incorporate the mixture and grind the soap flakes to a powder.
1 3 lb. box Super Washing Soda
1 4lb. box Borax
1 16oz. box Baking Soda
2 14 oz. bars Zote soap
Zote comes in pink and white. Both work equally well, but I like the pink because I can tell if the soap flakes are evenly distributed throughout the detergent. But again, this is just a preference.
I use our large roasting pan and the canning pot to mix everything. You need two large vessels to mix everything.
When it's all done I fill a 1 gallon glass jar, plus a half gallon Mason jar.
I use 2 level tablespoons per load and all my load are large loads. (I rarely wash small loads)
I usually get my ingredients at Wal-Mart, it's our closest grocery store.
Here's the price breakdown:
Washing Soda $3.97
Baking Soda $0.54
Zote ($0.97 x 2 bars) $1.94
There are 256 tbsp in a gallon
The recipe makes 1.5 gallons so that's 384 tbsps
divided by 2 because I use 2 tbsp per load, equals 192 loads
$10.42 divided by 192 loads equals $.054 per load
So one half penny per load!
I recommend that you read the owners manual on your washing machine before using this soap recipe. Or contact the manufacturer to see if powdered soap is ok for your machine. We have an old top load washer and I haven't had any problems.
Here are photos so you can see the prices at the store: