Starting tomorrow, at Walgreens (10/26) you may be able to snag costumes for just $1.59! In the Walgreens weekly ad, they will have a $5 off ANY Halloween costumes coupon and at several stores, people have been able to find costumes on clearance. The ones above were only $6.59 so after your coupon, you will pay just $1.59 per costume.
Also, it appears you can get 3 different costumes and get $5 off of each one with this coupon. These ads will most likely be at the front of the store or at the cash register (if not, just ask your cashier).