Here is a map were black soldier flies can be found: webpage. I don't know hpw exact this map is, but according to the map they are not found in the Sydney surroundings.
Does it make sense to breed BSF when they are not in the area? Can I start with BSF bought in the pet shop? (I have to have a look first) HOw many BSF would I need?
ARe there other maggots I could breed when BSF are not in the area?
I found one page with actually a how to build breeder ( not a movie a text entry) which is so much better!
If a local pet shop is selling them, and your climate is amenable, you're all set. Just set up your bin and drop them in. Be sure that you let some of the "crawl off" of mature grubs sit undisturbed in the soil or mulch....somewhere out of the reach of birds, so that they will hatch into adult flies and repeat the cycle. It took me a couple of years and a couple of introductions from outside to get them started here, but I am in a dry climate with only a few niches damp enough for them. They need some moisture and access to water as adults. There are also plans available for breeding them the complete cycle in an enclosure, such as a screenhouse or greenhouse. The space needs to be big enough and bright enough for the adults to fly around and mate.
I am in Brisbane and have black soldier flies "hatching" in my worm bin over winter. I also hope to "cultivate" BSF larvae for chickenfeed with plans to dehydrate the larvae over summer for winter feed.