Been using Nellie's for over 5 years and will never consider changing. When you consider that you only use approx 1 tablespoon per load, it is very economical, actually.
I've mentioned before that my clothes come out smelling so clean and have no residue at all. I have been able to eliminate fabric softener so I factor that into the cost per load. Full disclosure: I sometimes add a scoop of Oxyclean to a white load, but not always.
dee