I have been hearing about this auction house for a while now.Where is it in Diablo 3 for PS3?
The console version(s) of the game never launched with an auction house and the PC version had it removed because Blizzard felt that it took away the core focus of the game (there were also some exploits that flooded trillions of gold into the game out of nowhere).
They ultimately felt that Diablo, at its core, was about killing monsters, exploring dungeons and earning loot from killing - not playing a virtual market.
It's no longer in any version of the game and will not make a return.
There isn't one. There was only ever an auction house for the PC, but even that was recently shut down by Blizzard.