Amazon offers the Nature's Bounty 16-oz. Protein Shake Mix in Decadent Chocolate for $8.40 with free shipping via the directions below. That's the lowest total price we could find by $3. In addition to protien, it includes collagen, fiber, vitamins B and C, electrolytes, and probiotics. To get this deal:

1. View the Nature's Bounty 16-oz. Protein Shake Mix for $9.90
2. clip the $1 off on-page coupon
3. check out via Subscribe & Save for a final price of $8.40

Be sure to cancel your subscription after receiving your item to avoid being billed for subsequent shipments.