I saw quite a few pins saying that a mixture of half borax and half washing soda would give you a good powdered dish washing detergent.
The first pass through the dishwasher left me really happy with the results but for whatever reason all subsequent uses of it left me with powdered residue on the dishes. Frak.
The use of white vinegar as mock Jet Dry in combination with the mixture didn't remedy the issue. Back to the drawing board I suppose.