Have you guys heard of Thred Up?
Limited Time Only! 25% off your first purchase of practically new kids’ clothes from thredUP. Use code: 25OFF at checkout. Today through Monday 2/4/13 at 11:59PM PST. New customers only, first purchase only. Cannot be combined with other offers. One code use per person. Does not apply to shipping.
You can request a bag from them…fill it up with your kid’s old clothes…mail it to them..and they will pay you for those clothes.