This reportedly costs 50-75% less than buying dishwasher detergent. I haven't made the calculations myself, but I did try it out and it worked at least as good as purchased detergent. Once I figure out how much I used to pay for detergent I'll try and do the calculations, b'n!
Here's the recipe:
1/2 cup borax
1/2 cup washing soda (Arm & Hammer makes it)
1/4 cup citric acid (aka sour salt)
1/4 cup kosher salt
Combine everything and use as you would your normal detergent. In the rinse aid compartment, you can add white vinegar (about 1 tablespoon). Everything came out sparkling clean! Borax and washing soda are available in the laundry section at Winco, and probably most grocery stores. Sour salt and kosher salt are, well, with the salts! :)
I'm hoping to calculate the costs soon. I don't know how much cheaper it is, but I do know it's cheaper, and it only takes a couple of minutes to combine the ingredients. I made a double batch this time, but next time I'll probably mix up a gallon or so.
Next experiment: homemade laundry detergent!