One of the best recipes for a DIY window cleaner is Alvin Corn, which comes highly recommended by Apartment Therapy. You'll need 2 cups of warm water, 1/4 cup of white vinegar, 1/4 cup of rubbing alcohol, and 1 tablespoon of cornstarch.
Another quick substitute consists of 1/4 cup of white vinegar, 2 and 1/2 cups of water, and a few drops of your favorite dish soap. You may want to use scented dish soap and — perhaps — essential oil if you dislike the overwhelming odor of vinegar.
If you plan to use this cleaner on your windows, you'll want to wipe it with a squeegee as it runs down rather quickly. For items with small surfaces, like glassware, spray the cleaner directly onto the microfiber towel to prevent wasting the product.