Here's another rule I'll be using. This assumes that you're playing all four sets together as concurrent adventures.
Marketplace:If you've built all four sets together, you end up with three "stores." Set these up as marketplaces next to each of the "camp" spots (the brown squares where players heal / rest between adventures). Players can only buy / sell at these points (between adventures). And since there's three opportunities to buy, don't necessarily offer all options at all marketplaces. I will be using the following division of items (using my Hench rule from above):
Marketplace 1 [After Draida Bay]: Staff, Axe, Sword, Dagger, 2 potions [Luck, Speed], 2 Hench [Yellow, Yellow]
Marketplace 2 [After Waldurk Forest]: Bow, Wand, Sword, Dagger, 2 potions [Health, Strength], 2 Hench [Red, Brown]
Marketplace 3 [After the Caves of Nathuz]: Bow, Wand, Axe, Sword, 2 potions [Luck, Strength], 2 Hench [Red, Yellow]
Players in my game will be given the opportunity to buy based on their "rank" in the prior adventure, determined by monsters defeated [with the Strength of the monsters being added to determine score], with "first to camp" being the tiebreaker."