I advise against resetting the leafs, they will sag over time..although in the
OP's case, the caravan will make it sag back to stock within a day. Waste of money. The one in the ebay link are likley custom fabricated leafs not just reset standard ones. But still, the price is just flamin insane!
Now that mik mentions it, Ironman make a helper leaf that bolts onto the top of the existing leafpacks that apparently work allright, could be worth a look at. They normally cost up to $130 dependin where you look and what sales are on.