Since I did the Achievement recently
http://eu.battle.net/wow/de/characte...ement#81:a2336
Option 1:
The fastest way to get BSB rep is to kill the bruisers with 1-5 players.
Option 2:
NPC: Shakes O'Breen (Respawntime 12s)
Location: Faldir's Cove (Arathi Highlands)
My goblin rep was only honored/revered and I decided to go the save way a keep all rep at exalted. So I did BSB rep a second time, till exalted and then went to grizzly hills/tanaris to get all the goblin rep to exalted with only pirate killing.
My rep farming took some time, because pvp activity was allways high thanks to CRZ, so I had to pvp sometimes between the farming.
BSB rep till exalted: ~21 hours
goblin rep most part in grizzly hills + finishing rev->exalted in tanaris: ~45 hours
ravenholdt was the worst, I had 19.999/12.000 prepared before cataclysm - I did LBRS only because CRZ/monk-reroller never allowed the "faster way" to get lockboxes: ~38 hours LBRS