It took me awhile here in NZ to buy the eco-friendly detergents because they usually cost more than the non-eco ones. Sometime in November 2008, I made the switch.
I first tried 2 different products and used them interchangeably. I bought next Generation and Ecostore. They are both sold at 1kg. Ecostore has laundry powder specific to front loaders, which is what we have; while next Generation can be used on top and front loaders.
It took about 3.5 months before we finished the 2. At the end of my experiment, I couldn't make a decision so I decided to stick to using both. They are cheapest at Pak N' Save, both for less than $8.
For a family of 3 with a toddler who changes clothes often, we finish 1kg box in about 5 or 6 weeks. We usually run 6 big batches a week. The clothes are washed clean, they smell nice, and with help from sunny days the hard stains disappear. They don't need to get mixed with any other product and we don't use softeners anymore. Oh, I also read that 1 tbsp of white vinegar is good as a fabric softener! I have yet to try that. I read that clothes would not smell strange after rinsing with white vinegar.
I don't plan to change to any other brand unless something eco-friendly comes up that's cheaper.
I've suggested these products to my co-worker who struggles with money but she's a little hesitant to buy $8 for just 1kg. She prefers the giant boxes at The Warehouse that aren't that good. I know this because we used to buy those large laundry powder boxes. Try these 2 and you'll save money.