Bazaar is practically a waste of time, but is useful (if you purchase diamonds) to buy up 3 epics of one type (mage hat for example) to meld into a legendary. This is even seen as wasteful by other players, but can fast-track a legendary. Although the gold for supreme that you can meld with flawless can be useful when short of a particular type of gear. The itens are refreshed automatically every 4 hours or 2 diamonds for instant.
Note: sometimes the refresh of list won't happen until a refresh otherwise it can stick at 0 sec.