If trade value is equal to the labor value of something, then how is it that the trade value can fluctuate so much? You emphasize its creation of value, but what of the destruction?
Instead of Pokemon cards, lets use a trend that came and went. The trade value of a Beanie Babies skyrocketed in the mid-to-late nineties. People were using it as an investment vehicle. And then the trade value plummeted. The Beanies themselves, the cloth and the plastic filling, remained unchanged through all of it. If a good is damaged, its value is permanently reduced (sans labor to repair, anyway). If trade value is reduced... doesn't matter. It can go up or down or anything tomorrow. You would claim that process is equal to value derived from labor?