The marketplace system in Age of Aincrad takes on the role of an Auction House in a generic MMORPG, but provides far more interaction between players.
In major cities, the player can visit a Sales Board, which allows them to browse all items registered by shop owners, regardless of floor or location. When a player stumbles upon an item they wish to acquire, the location of the shop with said item will be marked on the players map. Along with this, the shop owner will receive a notification, telling them that their shop is being located. When the buyer arrives at the sellers shop, it is up to them to negotiate a fair price for the item.
Placing an item on the Sales Board requires a small amount of COL.