Amazon offers the Colgate Baking Soda and Peroxide Whitening Toothpaste 8-oz. 6-Pack for $7.92. Add it to your cart via Subscribe & Save to cut it to $7.52 and grab free shipping. (Walmart charges a few cents more via pickup.) That's about $2 less than what you'd pay in other local stores for the same quantity.

Be sure to cancel your subscription once your order ships to avoid being billed for further shipments.