If you haven't heard about Schoola yet, you should check it out. It's an online resale shop that donates a portion of your purchase to schools for the purpose of purchasing supplies, instruments, books, etc. I enjoy purchasing from there for multiple reasons:
1. They support schools, as I mentioned above.
2. They offer lots of credits and will often email you coupons. I've been able to obtain a lot of clothes for my kids for free. If you use the link above, you and I will both get a $15 credit, including shipping.
3. I support the principle of reusing clothes and this website helps me do that more efficiently.