For Prime members only, Amazon offers the Quest Protein Bar in several flavors (Peanut Butter Supreme pictured) for $2 with free shipping. Plus, you'll get a $2 credit to spend on a future purchase of select nutrition bars. Assuming you'll use the credit, that's tied with our February mention and essentially like getting the protein bar for free. (It's a low by $2 after credit.) Each includes about 20g of protein.