How much does a Shamrock Shake cost? Suggested price is $1.89 for the small size (12 ounce), $2.69 for a medium (16 ounce), and $3.49 for a large Shamrock Shake (22 ounce.) Prices will vary by market, however. A few years ago, only about half of Mickey D’s locations offered these shakes. This year, you won’t have to hunt to find ’em.