Amazon.com: Ronnie Coleman Signature Series L Carnitine XS 3000 Liquid, Amino Acids Metabolism and Lean Muscle Strength Support, Stimulant Free, Sugar Free, Zero Carbs, Blue Razz, 16 Oz : Health & Household The supplements aisle at Costco is loaded with lots of prodcuts, here's what I think of a few of them. Does Costco Sell L Carnitine L Carnitine (500mg) NutraBio Brands Elemental Performance Multi Carnitine 2 Frascos de 60 Cp Kirkland Signature CoQ10 300 mg., 100 Softgels Costco