I came across this on pinterest and decided to give it a whirl. I'm pretty excited about it. Spend about $20 and have about a years worth of detergent! If you have children it may be more like 9 months worth, but still quite a savings AND no perfumes and dyes and all that garbage. made mine up today and am on my last load of laundry. I'm very pleased. Here's the recipe:

1 box of Borax (4lbs)
1 box of Baking Soda (4 lbs)
1 box Arm and Hammer Washing Powder (5.5 oz I believe)
2 small containers of Oxy Clean (about 3.5 lbs total)
3 bars of Fels Naptha soap

Grate the fels naptha up with a cheese grater. Or if you have a food processor or magic bullet (that's what I used and it was much easier than grating). Use a bucket lined with a trash bag. Pour all ingredients in. Mix together. Use about 1 tblsp per load of laundry. Then you can put it up in whatever you choose. I used the empty oxy containers, and then put the trash bag with the rest in a rubbermaid container in my garage.