insulating and gyprocking a music studio

Hi all
We've recently completed building a free standing music teaching studio in our garden in Canberra. It's interior floor dimensions are approximately 3x7m, with a ceiling height of 2.4m.
I'm currently trying to get quotes for insulation and gyprocking/plastering, using acoustic grade materials with resilient mounts for the gyprock. We're aiming to use R2.7 batts, and 12mm Fyrchek gyprock.
It's mostly for teaching piano, so we're not aiming for 'complete' soundproofing, just a reasonable reduction in noise transmission to the outside.
Does anyone have a rough idea how much a job like this will cost?