We have a dishwasher, and believe me, we use it, a lot. I don't want to think about what all could be in store bought dishwasher detergents, so I'm really wanting to make some of my own. Here is a recipe from the blog Be It Ever So Humble:
2 parts Borax
2 parts Baking Soda
1 part Salt
1 part Citric Acid
Combine, shake, and use about 2 Tbsp. per load. They also recommend filling the rinsing agent reservoir with vinegar.
I do believe I'm going to give it a try.