Teds has the Sigma AF 50mm F1.4 DG HSM Art for all lens mounts for $859 after Black Friday special and an instant cashback.
Ignore the price on the list page and go to the specific product page for the mount you want and you'll see the correct price.
I'll list the individual links below
Sony: https://www.teds.com.au/sigma-af-50mm-f1-4-dg-hsm-sony
Cannon: https://www.teds.com.au/sigma-af-50mm-f1-4-dg-hsm-eos
Nikon: https://www.teds.com.au/sigma-af-50mm-f1-4-dg-hsm-nikon