Rare items will play more of a part in Dragon Quest V
's sidequests than just the wireless Item Shop mode. DQV
features "special items" that can be collected throughout the game simply for the novelty of having rare items. Some items are found in dungeons, and others are actually purchased as souvenirs. Some items, like the Chizotto Compass, which marks your current location, have in-game use in addition to intrinsic rarity-driven value.
Your stuff can be displayed in a Museum found along the journey. Apparently, the more stuff you put in this special museum, the more visitors will come, who will in turn alert you to the locations of more stuff.
You can trade your special items wirelessly, and you can populate your shop with rare local goods.