Homemade Detergent, revisited

About a month ago, I calculated that homemade detergent didn't really save money versus buying value detergent on sale. However, I have had to revisit my calculations; in actuality I've been using half as much detergent for each load as I had anticipated. So each load actually costs me about $0.035 per load. I haven't tried using half as much value detergent; I don't know whether it would work as well or not. But it's the fastest way I can think of to save money on detergent - use half as much as you usually do, and see if you notice a difference.