Laundry detergent is expensive! Especially with kids, who can dirty 5 shirts in a single day. You can easily go through a bottle a month. So, to make things cheaper I make my own detergent. I've used it for months now and I cannot tell the difference in cleaning between the brand names and my own. Although I always keep a bottle of Shout nearby, just in case! ;)
You can find many recipes online for powdered and even liquid laundry soap, but I find using the powered much easier since I don't have room to store a 5 gallon bucket anywhere for the amount the recipes call for. This is the recipe I use to make my detergent. You can find all these items in the same laundry aisle as the big boys!
1 bar of Fels Naptha
1 1/2 cup of Borax
1 1/2 cups of Washing Soda