I recommend Nordstrom Rack as well- I've seen True Religion there recently. However, you may find some at TJM or Marshalls but it's really hit or miss. I just bought a pair of PDC jeans for my niece- yellow stickered for $5!! Also, Loehmann's expanded its childrens department. They may have some as well.
Also, Bloomie's is having a Shop for the Cause event today. I think most things are 20% off. My local Bloomies has a large premium denim section for kids.