Amazon has a 4-pack of costumes[amazon.com]for kids on sale for $15.99 when you apply coupon code 20F3KN47 at checkout.
4 capes, 4 masks, and a bag to keep them in.
The capes are silky, and very sturdy. The masks are firm, but also pliable so they are comfortable to wear for a while. We have these in our dress-up tote, and my kiddos love them! They're great for boys or girls.