I used the information posted on Simple Dollar Blog (http://www.thesimpledollar.com/2007/03/15/how-to-make-your-own-laundry-detergent-and-save-big-money/) as a guideline. However, I don't want to make 5-10 gallons of detergent at a time. This guideline makes enough for 1 gallon of laundry solution. By my calculations the cost is roughly $0.50 per gallon. This detergent gets cloth diapers clean. It hasn't noticeably faded any of my dark clothes.
1/8 C laundry bar soap (I used Zote)
1/8 C Borax
1/4 C washing soda
-Boil 3/4 gallon water.
-Add shaved or shredded bar soap.
-Stir until soap dissolves.
-Turn off heat. Remove from heat.
-Place borax and soda into a 1 gallon pitcher.
-Add soap soup to soda mixture.
-Stir until borax and soda are dissolved.
-Add enough ice to make 1 gallon total of solution.*
-Place by your washing machine.
I usually use about 1/2 C of solution per load of laundry. I have a top loading washer.
*You can let the soap soup cool before adding to soda mix. If you do this add enough cold/room temperature water to make 1 gallon of solution.