I'd say the most expensive clothing would have to be anything Couture. Ready to wear lines can get expensive, but it's not unusual to pay 2000-3000 for a sweater or a dress. When your getting into the 80 000+ price points for garments your looking at couture.

And denim prices can hit the sky, I'm pretty sure baby phat had a 1 million dollar pair of jeans.. Mind you it had a big diamon button on the front. But it goes to show you price should not be equated with quality..