how does the black market thing work anyways?

http://www.mmo-champion.com/content/2774-Mists-of-Pandaria-Beta-Build-15689
There is not much about the Blackmarket AH at the moment, as it was implemented on beta realms not so long ago. In time we should know more about it. The only thing we know is that there will be rare items, mounts and pets (Ashes of Al'ar for example).

thanks man :]

Anytime:D