Staples offers the Oral-B Power Pro-White Brush Head 2-Pack, model no. 80228978, for $8.99. Plus, Staples Rewards members receive free shipping. (Not a member? It's free to sign up.) That's $14 under the lowest total price we could find for a 3-pack. Each brush head is compatible with Floss Action, Pro White, Precision Clean, Sensitive Gum Care, and Dual Clean models. Deal ends March 3.