The Twilight Bazaar is a magical marketplace in Entombed that allows you to buy and sell items using trade coins. You can't earn trade coins in the dungeon any other way than selling items in the bazaar. Occasionally, items are listed in the bazaar by the Mysterious Merchant. These are often rare and expensive.
The Twilight Bazaar is only enabled for users of the full version of Entombed. It also requires an internet connection.
To purchase an item, you need trade coins. These are earned by selling items in the bazaar to other players. When you upgrade Entombed to the full version, your account is credited with a number of trade coins to get you started. After that, listing items is the best way to earn them.
To buy an item, you first need to search the bazaar for the particular item type you're interested in. You can search for all kinds of weapons, armor, and special categories (for some interesting items). You can only purchase an item if your character's lowest level is more than or equal to the level the item was found. For example, the Greatest Sword of Kobold Slaying was found on the 6th floor and listed in the bazaar. If your character hasn't been to at least the 6th floor, you won't be able to purchase that item.
To sell an item, all you need to do is have it in your inventory. Some items can't be sold. If they're worthless, special, a key item, or don't fit into the bazaar's categories, they can't be sold. Once an item has been listed in the bazaar, you can not get it back. If you cancel the listing, the item is lost.
You have the option to cancel any current listings you have in the bazaar. You can use this to remove an old listing to make room for a new one. You have a number of listing slots, but once these are filled, you'll need to cancel some to make room for anything else.
Use the bazaar statistics to recap how many trade coins you currently have and what types (and how many of each type) of items are available in the bazaar. If you find the bazaar has a type of item you want, but you can't find it when buying, it means that the item is too high of a level for your current character. Try delving a bit deeper in the dungeon and see if it turns up.
After you've sold an item in the bazaar, you'll be notified with a message. The message will tell you what sold, how much it sold for, and who bought it. You can remove your messages after leaving the message screen.