A friend has been using this website, m.goodrx.com, with success in finding lower priced prescriptions.
I entered in generic Lipitor (Atorvastin) as one of the most common drugs used. It showed a wide range of pricing (from $12.60 to $76.78) for the same prescription. Some of the more common chains were among the most expensive. They also provide savings coupons. It might be worth a try.