I think that is the major problem as well.
Having a lock up working space large enough to hold wood stock, tools and sufficient working space to teach in, while being able to safely store pupils guitars as works in progress that is hopefully vandal proof , isn't going to be cheap in Sydney.
Hell, a basic 2 bedroom unit in a average inner city suburb if getting at least $1000 per week rent.
It needs help / support from local councils if anything like this could ever work at a reasonable cost, and where it would have the most people wanting to do it.
DOH!
I just realized, I do have a basically unused church hall directly across the road from me, and I'm as about as close to the Sydney CBD as you can get... [It was only the upcoming election that made me think of the hall, as that's the local polling booth]