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.