If your a new customer you can get $15 off your first order - since there is no minimum you can get that for free (plus shipping)

Thred Up

Use coupon code LUCKY15 - it expires March 22, 2013

If you've never used thred up before - its great - gently used kids clothes (like new condition). There are plenty of items in the $2-$4 range so you can get 5-7 items for just the cost of shipping (around $7)