The cost difference is due to the TGA requirements in Australia comparted to Asia or India and the choice of materials and labs used by the surgeon you choose.
The costs associated with using reputable implants with a Zirconia bridge with custom milled titanium bar account for over half the fee you are paying a dentist in Australia. Cheaper parts not designed for the job or that have inferior strength properties will result in more complications with the final product.
This is something that is not easy to fix when you have returned to Australia. This is something we would see on a weekly basis in our clinic in the Northern Rivers.