Ah, therein lies the rub. I haven't figured all that out, but I have to admit it's unlikely that I can get the costs comparable with a commercial product you can find at Wal-Mart, considering the additional costs of shipping involved. The stuff is concentrated, as the sample size for one full load is only 2 tablespoons (one fluid ounce); but I haven't yet figured out the best way to ship it.
EDIT: I'm certainly willing to accept advice concerning the best method of shipping.