drbabs and kitchen butterfly are right on point, but you should always ask about a recipe before you buy your macarons because every dealer makes them with different variations. If your looking to specifically buy gluten-free macarons, there are plently on online macarons companies that will ship to you, such as Dana's Bakery in New Jersey. This is only one of many, but ask what kind of shipping packages they use because you don't want your macarons to show up at a lesser quality then when they came out of the oven!

Yes, macarons are gluten free - the key 'flour'/main ingredient is ground almond nut flour (referably blanched).

Macarons are generally made from egg whites, almond flour and sugar, none of which contain gluten. (You meant gluten and not glue, right?)