Does study in Australia cost something?

Yes, course fees are charged by the universities or institutions that provide the course that you intend to undertake. The fee you have to pay depends on the institution providing the study, your course and the target degree. Normally you have to pay more for university study (from A$ 7,500 per semester) than for an education at a TAFE institute (from A$ 4,000 per semester).
The course fees are shown by the education provider in either the offer of place letter or the confirmation of enrolment document.
In addition there are certain basic financial requirements for all student applicants of all types of student visas. All applicants must show that they are able to pay for their course fees, health cover, living costs (accommodation, food, transport, clothes) and travelling costs for the duration of stay in Australia. Overseas students have to show they can cover these costs.
To reduce the cost you should look for partnerships between your home country university and the Australian University, scholarships and government aid for students. When you are a genuine student you can apply for a visa with work rights while you are studying in Australia.