As of July 2026 · 50 listings tracked across Amazon, Walmart & eBay
Right now the best value is 11¢ per fl oz — Atkins Vanilla High Protein Shake, 15g Protein, Low Glycemic, Low Car… (132 fl oz, $15.16) on Amazon. See it on Amazon →(paid link)
Prices change fast and stock disappears faster — YMMV.
The pack-size trapThe biggest pack we tracked (204 fl oz) looks like the bulk play, but it runs 21¢ per fl oz — the 132 fl oz pick wins at 11¢ per fl oz. Bigger isn't automatically cheaper.
Median across all 50 tracked listings: 23¢ per fl oz. The worst deal we saw ran $1.81 per fl oz — same product category, 15.7× the price per unit.
The 12-month picture
This is our first month of tracked history for Protein Shake — the trend line starts here.
Lowest we've ever tracked: 11¢ per fl oz (July 2026).
How we figure this out
Once a month we pull live Protein Shake listings from Amazon, Walmart and eBay, read the honest quantity out of each one (fl ozs, in this case — the unit that actually matters), and divide the real price by it. Coupons that change what you'd pay today are applied; "subscribe & save" teasers are not. Then everything gets ranked by cost per fl oz, because a big box with a small number inside is still a small number.