Compared to what everything else cost in my quilt room, I find the cans (or now they come also in squirt bottles) of spray starch exceedingly reasonable. I use about three a year.
I only starch what I'm going to cut, when I'm ready to cut it.
Starch is one of my four must haves for tools.
Here, cans run from $2.00 on sale to $3.50 each.
I don't think starch will hurt septic systems, it is generally speaking only cornstarch and water, although I don't know about commercial additives.