amazon.com has a 15-Pack of Monster Rehab Energy Drink for $17.88 when you clip the 30% off on page coupon and checkout via Subscribe & Save. Shipping is free on orders of $25+ or Prime.

amazon.com also has the 5-Pack 16oz Monster Energy Zero Sugar Energy Drink for $27 – 30% off (checked save an extra box, eligible on first S&S order for this product) – 5% off with Subscribe & Save (cancel at any time) = $17.51. Shipping is free.