I actually really want to make my own laundry detergent. I'm ashamed to say I got a recipe for it off of the Duggar family's website.
The Jim Bob & Michelle Duggar Family
One thing I've learned to do cheaply in the last year is clean. You can clean almost anything with boiling water, concentrated dish soap, baking soda, and elbow grease. Bleach, Borax, and washing soda are all cheap to have on hand for cleaning various things--bleach for the toilet, Borax as a laundry booster and carpet freshener (don't use around pets, though it is also good for getting fleas out of carpet), and washing soda for removing limescale and soap scum. Use worn-out shirts and cut up old towels for rags. One thing to splash out on is gloves--the Playtex gloves last a lot longer than any store brand I've come across.
Manufacturers' websites with tips on how to use Super Washing Soda, Borax, and Arm and Hammer Baking Soda:
Usage Tips Super Washing Soda
http://www.dialcorp.com/documents/borax.pdf
ARM & HAMMERŪ Baking Soda - Tour Our House