Julia Gillard has announced that from July 2012, government charges may be added to the already-increasing Australia DIAC government visa fee.
This means that further charges may be added for each additional person in the Australia visa application - meaning charges for the spouse and children for the main applicant.
Details of the amounts of these fees in the Australia visa application are not yet confirmed.
So there is no reason to delay your application at all - if you apply now with ASA, your registered Australia visa agents, then you can miss these extra costs, and also avoid the new Expression of Interest scheme which also comes in from July 2012.
For your Australia visa assessment, just register at the top-right of the page, and you will get to speak to your own assigned Australia visa consultant, who will assess your options personally and unique for your situation.