I bought a few of these organic cotton bags at the Guelph Organic Conference in January, and had purchased the mesh-like larger produce bags at No Frills (I think) or possibly Metro in the past.
They are super handy for buying bulk nuts/dried fruit/pasta/rice etc. The produce bags are great when I remember to bring them to the store (if I don't have them I just annoy my cashier and have 5 loose apples or the equivalent rolling around). The small cotton one is nice for bringing dry snacks with me as I go around. I've tried using them for apples, raw balls etc but they just tend to squish and guck up the fabric. I stick to small mason jars or small tupperware for moist goods.
I use the tupperware because I have it, I wouldn't buy new plastic tupperware now. If anything, I'd buy tiffin tins:
or glass tupperware:
But also, saving glass jars as you use them is greatest (and free-est!). Try to buy products in glass jars when you can (pasta sauce, peanut butter, etc) and save your roommates purchases as well! You'll be needing them now, before you start making all your own preserves and don't need to buy any from the store!