so your business model is price match when required, otherwise charge as much as possible to cover the brick & mortar overhead, which as a rule, is about 8:1 -13:1 more than an online storefront.
Thus, the only person who should shop at GNC should shop for the best price first, and most certainly not rely that GNC is in any way competitive with the market except when required.
Moreover, as a franchise, you must purchase from the corporation and remit a certain percentage of sales for the fees and coop stuff. Thus your overhead is even higher than a corporate store so your ability to compete long term is probably not very good.