Nutrisport has pretty good selection & prices, no shipping of course as with online ordering. Often they give additional 10% off to gym members, 15% off to pers trainers.
GNC is for the general health community (GENERAL Nutrition Centers)- their supps, knowledge, inventory, & prices are not targeted to BB or fitness people- better prices abound.
See thread 'where does everyone get their supps' for many online options.