The cost of the audit will depend on the size of the scheme (number of lots) and the complexity of the finances. I have seen the figure of $10 per lot with a minimum charge of $80 quoted.
There would be no harm in getting a few ballpark quotes. Or you could contact our friends at the OCN for their advice.
The Australian Auditing Standards refers to the professional standards of the auditors, including them being qualified and independent – you can find out more HERE.