I'm putting an extension on the back of my house. I had a guy draw it up and quote on it.

It will be 2 stories and I was quoted 12500B/sqm. It is a 100sqm build.

That is A grade fixtures, tiles, sliding doors etc, Q-con bricks full western kitchen, bathroom and built in wardrobes in two rooms.

Another builder said a rough idea for homes is 10000B/sqm.

Is it too much or ok considering the use of A grade materials, kitchen etc? I'm just after a rough idea and not getting into a debate about it, obviously there is a lot to do selecting fixtures and checking the quality of the wood work.

I searched and found nothing, maybe a handy guide for those considering building?