2 Gallons of hot water
1 Bar of soap, grated
1 Cup baking soda (if you have it available in your area, washing soda can be substituted)
1 Cup Borax
Put about two quarts of water in a sauce pot, add grated bar soap, baking soda (or washing soda), and Borax, and heat until soap is melted and baking (or washing) soda and Borax is completely dissolved. Put remaining water in a bucket or sealable storage container. Add the cooked mixture and stir until incorporated. Use 1/2 cup of the solution instead of traditional laundry detergent. Mixture will need to be re-stirred prior to each use, as it can clump up.
This recipe costs about $1 to make each batch, depending on the kind of bar soap you decide to use (I splurged and got the Hypo-Allergenic Pure & Natural Almond Oil and Cherry Blossom, which raised the cost to about $2.50/batch).
I haven't tried this one yet, but I will when I start hanging my clothes outside this summer:
2 Cups baking soda
4 Cups hot water
2 Cups WHITE vinegar
Dissolve the baking soda into the hot (almost boiling) water.
Add white vinegar.
After solution is done fizzing, store in a 1 gallon jug.
Add 1/4 cup of mixture to the final rinse cycle.
The place I obtained this recipe swore that it did not leave clothes smelling like vinegar. You can also add essential oil for fragrance if you choose.