The dishwasher is one of those amazing household conveniences that most people think you need to buy soap for. I've recently learned otherwise. I had used the electrosol tabs - they're pre-measured and I like that... no guessing as to how much powder/gel you need per load. But, this can get a little pricey. So, I started looking into inexpensive alternatives.
Borax and baking soda with a little castile soap are decent alternatives. I have mixed equal parts of both, thrown in a few drops of castile soap. Put in the cup dispenser and run as usual. The only issue I've found with this is sometimes there is food or a white residue left on certain items. I have read that adding white vinegar to the rinse agent dispenser works, but as I still have jet dry in mine, I can't say for sure how well this works.
White vinegar, baking soda and a little of my homemade laundry detergent seem to work pretty well. I add a tablespoon or so of baking soda to the cup dispenser, slowly pour in the vinegar - 2Tish - and then top off with the laundry detergent. I sometimes put vinegar in the pre wash cup. This is much less likely to leave the white residue, but I do need to make sure most food has been scraped from the dishes and silverware - particularly things like egg and cheese. Otherwise, this works well. :)