Reccommended small builders in Melbourne for extension

We have recently bought a small renovated 2 BR California Bungalow in The Northern Suburbs of Melbourne, and we are having great trouble trying to find a recommended builder whose costs aren't excessive. Our quotes have been rather expensive as most places that do extensions offer the full service (eg, getting council approval, designing/ architects etc). My father is our architect so we don't need this service. We found 1 so far that was recommended, and he quoted us reasonable price (70m2 single storey extension for around 180k), but just hoping someone could give us 1 or 2 more other small builders that they have built with that they recommend.