Pick up this set of 3 Fold-Up Reusable Nylon Shopping Tote Bags 3 Colors for just $4.99 and they ship free. I love these because they fold right up and fit in your purse, so you don't have to remember to carry in your bags. I forget my reusable bags half the time, but if they were in my purse, I wouldn't!
You get 3--one each in green, black and pink.