Been to a couple different Vitamin Shoppes, mostly in the Long Island/Westbury Area but also in Brooklyn, they're carrying a bunch of 2.5 lb jugs of Tetrabolic (comparable to CytoSport's Muscle Milk) for $15 a jug.

http://www.VitaminShoppe.com/store/en/browse/sku_detail.jsp?id=VS-2553

Link is to the product information.

It has a really good nutritional profile, though it tastes kinda chalky. They're on sale for 50% off because the expiration date on them is November 30, 2008, but shouldn't be a big deal if you go through protein quickly! Last store I checked was the Garden City one, and there were probably 25-30 jugs on the shelves of the Cookies and Creme flavor.