Dishwashing soap costs
I bought some of that Dawn foamy dish washing soap about a month ago because my sister-in-law has it, and it is rather convenient. I thought I'd use it up and then see if I could put some regular dish washing soap in it because regular dish washing soap is about 4 times cheaper than the refill foamy stuff. I mixed some of my cheap Ajax about half and half with water, and it worked! I still have the undiluted Ajax to use on really tough grease, but the watered down version does just fine for most things. I figured that Dawn had just diluted their soap in order to make it go through the pump and foam up. Obviously, that's what they did. :-)
I haven't done a "scientific" experiment to discover just exactly the proportions necessary, I just put a small amount of water in the dispenser and added about that much Ajax. I'm sure I'll refine the exact amounts in the days to come.