Face it, there's no need for these things and they are destroying the planet. China has outlawed them, Ireland has taxed them, and hopefully soon the US will start dealing with the problem as well. Plastic bags create a tremendous amount of waste (over a million enter US landfills a minute) and waste a great amount of petroleum since that's what they are made from.
Your best bet is to get some good
re-usable bags. They range anywhere from 99 cents to a few bucks and each one (or at least a well made one) will replace thousands of plastic bags over it's lifetime. On top of that, with a 5 cent back per bag refund from most grocery stores, they'll actually pay for themselves and then keep making you money.
Your best bet is to have a few by the door, a few in the car, and one in your purse or bag (
Chico bags are small enough to fit in there without getting in the way). Whole Foods sells a
good full size bag for 99 cents that's made from recycled bottles and has a lifetime warranty (they'll replace it for free).
On top of that, take the pledge and just say that you'll never take another plastic bag again. After that, you'll find yourself at the store once or twice without a bag and have to juggle things out, but trust me, that'll convince you pretty quickly.
PROS: Better for the environment, better for your pocket, actually saves you money over the long run.
CONS: Takes a little while to get used to keeping bags handy but eventually you won't even think about it.