She can make those packs go a LONG way, given enough rising time, with superior flavor to boot. E.g. the pizza dough with poolish in Ken Forkish's book "Flour Water Salt Yeast" uses 0.4g dry yeast per 1kg of flour.
I've been buying instant yeast at a restaurant supply store for $5/lb, decanting into 8oz Mason jars, and selling it to neighbors. Something like 5lb so far.