I'm in Perth, Western Australia...
Favourite roaster for my standard morning flat white is Leftfield. All their roasts are blends on the medium/dark side, but consistently high quality.
(And... I just looked at their website for the first time in ages and see that they now have a whole bunch of single origins...)
For coffee nerd stuff, I like community coffee and blacklist. Blacklist are a third wave coffee shop, they do a whole heap of single origin roasts and do pourovers, etc, in the cafe.