Just use half of the recommended amount of detergent on your washing machine. This will keep your expenses low and stills cleans you laundry well. It's common for many companies to say you need more detergent than you really are. The trick is, the faster your bottle is empty, the more often you need to buy new stuff. Just try it, it works.
Besides that what the article is saying, try also to use from 1/4 to 1/2 less fabric softener. If you have a good one, you can easily half the amount of that, too. The laundry still smells great and is soft enough. And again, it not only saves you money, but protects the environment greatly.
Just try it, you might not regret it.
[via Lifehacker: Save Money by Using Just Half the Laundry Detergent Recommended]