Update: That $15 coupon is gone, but this box with 20 strips and two express one-hour treatments has a $5 coupon, which brings it down to $39.

Let’s say you’ve already upgraded to a good toothbrush; what’s the next step for cleaner teeth? Judging by the excellent user reviews, this 14-count box of Crest 3D Whitestrips is a great place to start. Just be sure to clip the $15 coupon before you check out.