For new customers only, Soap.com offers the Crest 2-Hour Express Whitestrips 4-Count Teeth Whitening Kit for $11.23, via the directions below. Combined with free shipping, that's the lowest total price we could find by $13. It includes four separate treatments. Rebate ends August 25. To get this price:
  1. Search for "92320" to find the Crest 2-Hour Express 4-Count Whitening Kit for $40.99
  2. apply coupon code "GOSUMMER" makes it $32.79
  3. redeem coupon code "SOAP20AFF" drops it to $26.23
  4. send in this $15 mail-in rebate for a final price of $11.23

Of note, the Crest 3D White Whitestrips Enamel Safe Professional Effects 20-Count Box (search for "60965") is available for the same price via the above coupons and this $15 mail-in rebate, another low.