I love foaming hand soap. I hate the price. One day I decided to try using regular liquid hand soap and watering it down, just to see if it will work. Well, it did. I came to find out that this isn't some amazing discovery on my part, but that many people do this already.
I bought the foaming pump. Once the soap was gone in it, I refill it with a solution diluted to 1 part liquid soap to 2 parts water. Sometimes I dilute it 1 part soap to 1.5 parts water. Different brands have different consistencies of soap. I stir it gently to dilute the soap. Not only do I get to have my wonderful foaming soap, I'm saving a whole lot of money.