Amazon offers the Wrigley's Doublemint Chewing Gum 5-Piece Pack 40-Count Box for $6.99. Check out via Subscribe & Save to knock it to $6.64. With free shipping, that's about a buck under what you'd pay in-store, outside of the mention below.
A close price: Walmart has it for $6.98 with in-store pickup. Be sure to cancel Subscribe & Save once your order ships to avoid being billed for subsequent shipments.