Most places have the cheapest 3.5kw system for $800-$900
The good guys ($848)
https://www.thegoodguys.com.au/kelvinator-c35kw-h40kw-revers…
Bing Lee ($939)
https://www.binglee.com.au/lg-p12awn-14-3-5kw-4kw-inverter-s…
Harvey Norman ($848)
http://www.harveynorman.com.au/heating-cooling-air-treatment…
Betta ($828 after cashback)
http://www.betta.com.au/teco-air-conditioner-rev-inverter-wa…
Kogan 5.1kw system ($869) is a good price if kogan floats your boat.
https://www.kogan.com/au/buy/kogan-51kw-split-system-air-con…
At time of purchase there were 7 in Auburn and 8 in Castlehill, but more can be ordered.
This is a run out model, which has a 60 month warranty.
This seems like a good price, especially because there's another 40 degree day coming up on Tuesday in sydney.
Yeah but, Convair… You get what you pay for.