After seeing several version of making these environmentally friendly bags, I chose this tutorial:
Other ways of making them used oilcloth for a lining and a cloth fabric for the outside. Those are great options for making sandwich/snack bags as they're food safe. But, personally, I like seeing what's inside.
I chose the filmy vinyl plastic because it was way easier to sew. It didn't actually stick at all on the foot, which is a HUGE bonus when working with plastic.
I bought the fabric at Hancock Fabrics and it was only about $1.29 for a whole yard! I got half a yard and still have enough to make probably...10 more of the size I made? I made mine a little on the bigger side with finished measurements of 8 1/2"x7 1/2".
NOTE!!! I've since learned that this particular fabric I used isn't food safe. It contains PVC which has bad stuff for your food to be in contact with. This is why it's now a storage bag only.