Ammonium sulfate is somewhere around .25 per lb.   It is a nitrogen fertilizer and also is used to buffer hard water to improve the effectiveness of glyphosate.  I don't see how laundry detergent is going to accomplish either of these goals.  10-34-0 will provide the N source but is not as good at conditioning spray water as the AMS. 

The detergent would perhaps work as a surfactant, but these days most of the glyphosate products on the market already contain surfactants in their formulation. 

On a related note.....the pink lotion type dishwashing liquid from Sam's that costs about $3.65 per gallon makes foam just as well as the $15/gal plus foamer from the dealer.   I do use a little more of it, but I also make better foam then I did at the higher price and lower rate.