My wife has bought and sold a fairly large amount of vintage Barbie stuff. Those carrying cases should do pretty well. Check the clothes for tags with the Barbie logo. If they are in good condition, those items should do better than clothes without the Barbie tag. Look for pieces that go together (like suits) and sell them as a set. Even the small accessories like shoes sometimes bring $5 or more. Heck, even the miscellaneous little items sell.