I find Sta-Flo in the laundry area of the local grocery store. It comes in a blue quart size plastic jug. Some Walmarts carry it. Depending on where you live, you might have to go to several places to find a store that carries it (or request it at the customer service counter of your favorite grocery).
I always use that heavy 1:1 solution on flannel. The flannel comes out about as stiff as lightweight cardstock, so it is *not* going to move anywhere while you work with it. Makes it easy to piece accurately too. It's preferable to starch before cutting, but I think in your situation it would be well worth the effort to starch your cut strips before you go any further.