I came up with a dry version of this soap about a year ago. It works very well. :)
I use:
1 - Bar of VERY FINELY grated Fels Naptha Soap
2 - Cups Borax
2 - Cups Washing Soda
Mix together. Use 1 tablespoon for regular loads, or 2 tablespoons for heavily soiled loads.
I have to order the washing soda and Fels Naptha soap online, but even with shipping, it's still cheaper than buying ready-made soap at the store. And sometimes it's possible to get free shipping if you check around.
Also, I've substituted Octagon soap or Ivory soap instead of the Fels Naptha, and they worked just fine.
I also have a method for stretching my liquid fabric softener. A bottle lasts at least a year. I get an empty spray bottle, and put 2 parts of hot water and 1 part of fabric softener. Shake well. When I'm ready to dry a load of clothes, I just spray 10-12 sprays into the dryer, and dry the clothes as normal. Works just fine! :)