Amazon has the TropiClean Oatmeal Medicated Dog Shampoo (20 oz) for $11.99 - 25% off coupon (check "Save an extra" box, eligible on first S&S order for this product) - 5% off with Subscribe & Save (can cancel at any time) = $8.39 with free shipping on $25+ or with Prime.

Sells for $12+ elsewhere.