Hi Neva,
I agree with Ash above in that you should ask the doctor/hospital for a breakdown of the fees. It could be that the fee is reasonable considering the amount of records they need to transfer over and where to. However, you have a right to enquire about this.
As a patient, you have access to your own records. It may be cheaper to request a copy and personally send/deliver it to the new clinic. Unfortunately, as far as I know of, SA does not have capped fees for requesting medical records. To give some reference, Victoria has a schedule of maximum fees clinics may charge for records:
"Access to health records and maximum fees for access"
If you still dispute the figure, or wish to gain some more information, you can contact the
SA ombudsman (which is also the unofficial health ombudsman).