Amazon offers the Chemical Guys Maxi-Suds II Car Wash Soap and Shampoo 1-Gallon Tub in Cherry for $15.29. Order via Subscribe & Save to drop it to $13 and bag free shipping. That's the lowest total price we could find by $5, although we saw it for $3 less last June.

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