Amazon offers the Affresh Washing Machine Cleaner 6-Pack for $11.99. Checkout via Subscribe & Save to drop it to $10.19 with free shipping. (Lowe's offers it for pennies more.) That's tied with last week's mention and the lowest price we could find by a buck. They are designed to remove odor-causing residue that can occur in all washing machines.

Note: Be sure to cancel your subscription after your order arrives to avoid being billed for subsequent shipments.