MIght as well go get a humidifier if this is your idea, they're not expensive and won't add so much heat to your space. I would just put a bowl of water with your fan blowing on it. Actually I would spend $20 or less on a small humidifier, but I guess if you are trying to be ghetto the purchasing may not work.
Give your window A/C a break and replace it with a window "Swamp Cooler", it will run a lot cheaper and ad moisture at the same time!