Simple answer is:
1) Each miner needs a PSU for that miner.
2) To achieve your goal of 100 TH, you would need a minimum of 1 controller - these run up to 20 Avalon Miners.
That 1 controller will only require 1 Ethernet connection so you likely won't need to upgrade your router or anything of the sort.
I've only ever dealt with Blokforge, but you can also check out
cryptouniverse for Avalon products I believe they are also offering discounted miners. As for looking for other Miners in Australia, you can try out the Marketplace section -> Goods ->
Computer Hardware.
Thank you for that.
I might have made a fatal mistake though - the power cost per machine. The hashrate might be 100 to 120 TH/s, which is nice to rent out on Nicehash or MRR or elsewhere, and I do have cheap electricity out at the farm, but I didn't know I needed a PSU for each machine, so thank you for the clarification. I will have to check to see if I can recover electricity costs a bit more before I go all out.
I think it seems the most profitable machines for me that I can afford would be the Innosilicon A9 ZMaster (definitely), Innosilicon A10 ETHMaster (good, but apparently not quite as good as the ZMaster), or one or two big BTC miners that are more energy efficient rather than a batch of smaller ones.
Thanks so much, I will check out the Marketplace as well.