salary of a straddle/crane driver in sydney australia?

You're wasting your time even thinking about it. Employers are only allowed to sponsor workers who have acceptable qualifications in an occupation listed on the SOL or CSOL - that occupation is NOT on either list. Here are links to the lists so you can check for yourself:
http://www.immi.gov.au/Work/Pages/skilled-occupations-lists/skilled-occupations-lists.aspx SOL and CSOL

Australia doesn't need crane drivers, therefore, you will not be able to immigrate here.

It's not as easy as just packing up and coming over, you know.

You should hunt around on Google for various jobs available and see what is on offer. It seems that gantry crane operators in general earn $50,000 to $75,000 a year but you would need to check different companies.

Crane Drivers Salary

Cornwall, Ozmaniac has given you some details, but "K" is more to the point. I didn't see your occupation on the skills list.

Let me go a bit further, your so called friends in Australia, gave you a useless piece of information or irresponsible advice. Companies do not like going into bed with Governments.

Companies sign and agreement with the government, stating they will be responsible for you, and no companies are prepared to do that, unless your a prospective CEO with earnings over $500K per year.

If your thinking of uprooting your family for $75K (if you have a family), you need physiological help..

I didn't find anything which specifically pertains to straddle/crane drivers but here is a list of driver jobs in Australia which might help: http://www.payscale.com/rcsearch.aspx?category=Job&str=stradle%2Fcrane+driver&CountryName=Australia&SourceId=Country .