There is very good chance that you will get Australian visa as a Nurse.
Visit
http://www.immi.gov.au/skilled/medical-practitioners/nurses.htm

This site will guide you well. You don't need any agents help. You contact the relevant authority in Australia. They will guide you if needed.
I have done all by myself. Its easy.
Contact me if you need any help. I shall help you & its of course free of cost.