You probably already know this one....but anyway......
The dial foaming soap is over $2 for that small bottle. The ginormous S*m's liquid hand soap is about $8 (can't remember exactly)....we've been using this giant bottle for about a year.
Use 3 parts water to 1 part soap, stir, ever so slowly (to not foam up), and add to your foaming soap dispenser.
When 1 runs out at our house, I make the refill recipe in a 4 cup measuring cup, and top off all of the soaps in the house. Any leftovers can be stored in a glass jar.
I feel sure this little trick has saved us close to $500 in a year, based on at least 1 refill per bottle, per month, times 3.5 bathrooms and the kitchen sink. And who wants all those little plastic bottles in a landfill anyway?