An Auction house is special Structures where items for sale can be searched. Items are listed for a price in spices. All spices have the same trade value. A buyer can purchase items remotely, but a 20% delivery fee will be added (rounded up). To avoid the fee, click on the "Without fee" button to get a directional pointer to the location where the item is being sold. It is possible that another player could buy the item before you arrive at the location.
Items are put on sale at a Vending stand or a Store.