ThredUP is having a 48-hr Halloween Costume Sale through 9/21. ThredUP is offering new members $4 off their first thredUp box of gently used costumes, clothing and more- making it only $1 plus shipping (which is $11) with coupon code: costumes at checkout. Each box contains about 10 items. You get to look at what items are listed in each box to decide if it's what you want.
If you aren't familiar with thredUP, it's an online community where you can purchase a box of preloved kids clothes & toys. The boxes normally contain name brand clothing.