Amazon offers the Philips Sonicare E-Series Replacement Toothbrush Head 2-Pack for $17.60. Clip the $5 off coupon and check out via Subscribe & Save to cut it to $11.72 with free shipping. That's tied with last week's mention and the lowest price we could find by about a buck.

Note: Be sure to cancel Subscribe & Save once your order ships to avoid being billed for subsequent shipments.