I recently purchased a grocery bag from a grocery store for a few dollars.  The clerk rang up the rest of my items and placed them in the bag and informed me I get a few cents off for using the bag, which surprised me.  Come to find out, a lot of grocery stores are doing the same and in the end, everyone wins.  Also, I made a commitment that if I go to any store and purchase something small that I can hand carry, I will deny a bag.  It saves the store money and it saves the earth one less bag in a landfill.  That was my effort in going green.