8/14/16. Costco offers a great selection of some of the most popular Halloween costumes for children. Shop in stores or at costco.com. While supplies last. Disguise Toddler Licensed Costumes: $15.99 (Item #949507) Rubies DC Superhero Tutu Costumers: $18.99 (Item #9497899) Sizes S, M, L Teetot Princess Factory Costumes: $19.99 (Item #949488) Sizes 3-4 and 5-6 Disguise Halloween Costumes: $17.99 (Item #949504) Sizes 4-6 and 7-8 Rubies Toddler Licensed…