The Homeless Children's Playtime Project (playtimeproject.net) collects new and gently used costumes every year so the children they serve have costumes for Halloween.
Anonymous
10/22/2012 13:40
Subject: Old Halloween costumes
I donate some and eBay others (the ones that are in really great shape). I also buy them from eBay. If they're only worn once it makes perfect sense and you can find great costumes that way.