Trading House of Praetoria
The Trading House of Praeotoria is the only consignment store in the whole city-state. It is located in Imperial City. Operatives are allowed to buy and sell items here using a "secret bid" system.
The Trading House also serves as a special museum where extremely rare items are put on display. These are items that were salvaged from those pre-Praetorian days before the Devouring Earth decimated the world.
It is rumored that there is also an operative from the Trading House found in the underground tunnels, however that information cannot be confirmed or denied.
(Please see the Paragon Wiki entry for more information.)