Development Costs

Hi All,

First time positing. Would like to get the communities knowledge on development costs.

Am looking in regional Victoria for opportunities to put either 1 or 2 units behind an existing house.

Would appreciate if anyone could note down the general costs associated with sub-dividing and building.
e.g What does your average 3 bedroom single story unit cost to build?
What does sub-dividing cost and so on.

Would be great if anyone could link me to similar existing discussions.

Thanks