Phosphate free dishwasher detergents cost a fortune, even though they are made of very simple ingredients.
From TheNewHomeMaker.com comes this recipe for a DIY dishwasher detergent:
1 cup baking soda
1 cup borax
1/4 cup salt
1/4 cup citric acid (which can be bought at a winemaking store, or might even be available in the grocery store with canning products)
In addition, vinegar makes a great rinse agent instead of Jet Dry
If you make it, let me know what you think.