Everyones best friend when it comes to getting rid of junk is eBay. Online auctions are a sure-fire way to turn that sleeveless jacket (which came in and out of fashion in a week) into hard cash.
Some eBay sellers look at trends and try to predict what will be big ahead of the market. If you are good and dont mind taking a risk then you can buy early in bulk and sell on when the craze hits.