Head over to your local Sears and buy a box or two of this. It's good laundry detergent, and once or twice a year they put it on sale for half price. At $10 per 180-load box, that comes to about 5.5 cents per load of laundry.
IIRC, it came in about sixth place out of 25 detergents in Consumer Reports. It wasn't ranked as highly as Tide or a couple other premium brands, but it was about 1/6 the price of those. It's actually cheaper than the 99-cent store stuff that ranked rock-bottom in the CR ratings.
In other words, it's the best deal around. Grab a box while it's cheap.