Mages must be level 10 to create, buy or bid on a listing. you may browse if not level 10.
It is not always available.
On August 9th, 2013 it was announced that both the Bazaar and the Auction House would remain closed until TinyCo announce otherwise. It is not expected that the markets will return in a short timeframe.
Beta for the Auction House ran April 22 - April 25. Players were invited to join on the 14th of May and the Auction closed a few days after.
The Auction House enables players to put a card up for sale and set a minimum price, other players can then bid to be the one to buy it.
Mages may view cards listed and make up to 10 different bids in Energy potions and Battle potions (Coin transactions are currently disabled due to a bug affecting a small number of players, but this will be fixed in the next app version.).
When viewing the listing you need to refresh the bid info and it will show the highest bid, if you have the resources in your inventory you may place a competing bid, if not the option will not be available to you.
The Bazaar enabled players to sell, trade or buy cards from each other. Purchases are made instantly.
Mages may view, search and sort cards listed. If you can pay the price in Cards, Potions or Coins you can make a purchase. Cards in your battle deck need to be removed before you can trade them.
You can also sell your cards and set a price for them by creating a listing.