This is an insane price for Australian stock of the Sport version of this lens. We're talking $400-500 cheaper than other Australian stockists, and $300 cheaper than grey market.
Sadly you need to add $275 for the Nikon or Sony A-mount version.
Keep in mind there are two versions offered by Sigma in the 150-600mm zoom range: the Sport (S) and the Contemporary (C).
The difference? The Sport version has a sturdier metal casing (instead of plastic), full weather sealing, larger and smoother focus ring, better focus accuracy and marginally better optical quality across the zoom range. This comes at cost of being quite a bit larger, heavier, slightly slower to focus and more expensive than the Contemporary version.
I recently got the Contemporary version for my Sony a7RII (adapted) and it's surprisingly sharp even at 600mm wide open. Teds currently have the best deal on the C version with their Friday the 13th sale, ending tomorrow, where they offer a $100 coupon on top of a discounted price ($1218). I managed to get mine for $1199 at a Camera House locally prior to this deal (but the Teds deal is better).
Shame it's an extra $275 for the Nikon version. Fantastic price if you've a Canon.