What I used to make my own dishwasher detergent is Ingredients Used : Borax
Super Washing Soda
Citric Acid (I got this at Wal-Mart for $2.97 a container for 7 ounces, Amazon $7.00 for 1 LB)
Kosher Salt

Option to use 7th Generation Dishwasher Detergent or whatever detergent you like to use

Take 1 cup of Super Washing Soda, 1 cup Borax, 1/2 cup kosher salt & 1/2 cup of citric acid. Mix together and you can use that for the dishwasher detergent. I use 1/8 cup of detergent per load in my dishwasher (Bosch)

I had found that after a few loads the dishes were not getting clean and had some weird debris on them. I had read to use lemon kool-aid in the mix which I tried and really did not notice much of a difference. I tried 1 packet all the way up to 8 packets per batch, and the dishes came out the same.

What I did try that worked, was to take the 3 cups of dishwasher detergent that I made, and then mix in 3 cups of the dishwasher detergent that I had previously been using, which is 7th generation. That gave me a total of 6 cups of dishwasher detergent and it seemed to clean the best (even better than using 7th generation by itself)

Cost Per Load:

I use 1/8 cup per load in my dishwasher (Bosch) Without the 7th Generation it comes out to be 12 cents per load (3 cups total) With the 7th Generation it comes out to be 10 cents per load (6 cups total)