Because of how often I have to refill the kids' soap dispensers, I suspect we save nearly $100 per year on hand soap by following this recipe from Thrifty Fun:

http://www.thriftyfun.com/tf29957105.tip.html

Buy one foaming hand soap dispenser per sink but DON'T buy the "foaming hand soap refills".  You're paying way more than necessary for foaming hand soap if you do that!  Instead refill an empty foaming soap dispenser with just two tablespoons of regular liquid hand soap (store brand works) and then add 1 cup of water.  Same stuff... a fraction of the price.  It works!