http://www.amazon.com/Anseahawk-Assorted-Strawberry-Shopping-Reusable/dp/B014MFA2TW
Clearly, someone traveling on foot is not going to be able to carry a trunkload of groceries, but a couple of these fit-in-your-palm (and purse or pocket) beauties can carry more than 5 flimsy plastic bags. The alternative is to let the store keep 5 cents per bag. 