Mixing your own fixer is pretty easy. Sodium Thiosulphate - 240 grams, Sodium Bisulphate - 23 grams - water to make 1 liter. Based on photoformulary pricing at 50 lbs for 96 batches it comes to $2.36 a liter. I guess it does about 20 8x10 a month. There is really no magic to it. Just get a cheap postal scaleor used balance off e-bay.
Frank