Would need some advice from the experts here.

We are 28 years old.
I am an electronics engineer and my wife is an accountant.
We got a baby.

How is the steps of migrating to Australia and how much money do we need to prepare in order to do that?
The first thing is sit for IELTS test?

For the immigration fees.
I heard the application fee is AUS $3.5K and the test is about $500 per person.
Is that true?
Does our baby need to pay for the fee also?

Thanks in advance for your help.