Amazon offers the PetArmor Flea & Tick Treatment for Small Dogs for $9.69. Check out via Subscribe & Save for a final price of $9.21 with free shipping. (Target charge the same price via its own subscription service.) That's the lowest price we could find by $26, outside of the price below. It contains three monthly doses.

Be sure to cancel your subscription once your order ships to avoid being billed for further shipments. A close price: Walmart charges $9.98 via in-store pickup.