The Australian Association of Flight Instructors says that the rate for a casual Flight Instructor Grade 2 is (SE) $50.74 PH. NVFR SE $52.40.
Givn that one hour of flight instruction typically takes 90-120 minutes to brief/pre-flight the aircraft/post-flight secure the aircraft/debrief the student etc. the rate per hour should be in the order of $70 PH for an instructor employed as a casual.