As one of its daily deals, Staples offers the 10-Day Smile System, model no. GS12088-0010, for $29.99. Plus, Staples Rewards members qualify for free shipping. (Not a member? Click here to sign up for free.) That's $120 off list and the lowest total price we could find. It features preloaded trays that whiten upper and lower teeth with a cool mint flavor. Deal ends March 10.