Amazon offers the Luna Bar 1.7-oz. Bar 15-Count Box in S'mores for $12.50. Add them to your cart via Subscribe & Save and the price drops to $11.87 at final checkout. With free shipping, that's about $9 less than what you'd pay in local stores.
It's also available in Blueberry Bliss for $12.57 before the Subscribe & Save discount, $11.94 with free shipping after. Be sure to cancel Subscribe & Save once your order ships to avoid being billed for subsequent shipments.