Toys "R" Us cuts up to 80% off boys' and girls' costumes as part of its Halloween Clearance. With prices starting at $4.99, many items are at lowest-we-could-find prices. Shipping starts around $5, or get free shipping on orders of $49 or more. Sales tax is added where applicable.

A best bet is this Batgirl Halloween Costume in Medium or Large (pictured) for $9.99 plus $5.28 for shipping. That's the lowest total price we could find for this costume by $2. It includes a dress, mask, arm gauntlets, boot covers, and belt.