Amazon has the 7oz Nizoral A-D AntiDandruff Shampoo w/ 1% Ketoconazole for $16 - $3.17 off coupon (check "extra savings" box, eligible on first S&S order for this product) - 5% off with Subscribe & Save (cancel anytime) = $12 with free shipping on $35+ or with Prime.

Only use twice a week to control flaking, scaling, and itching caused by dandruff (kills the fungus at the root).