I got them through VPW in Epping. They are the local Kirkey dealer. They are available in various widths to suit your car (Or your behind).
The price from VPW was pretty good but I had to wait 6 months for them to arrive. Lots of delays for them getting them since they are made in Canada and then shipped to LA before going on a ship to Melbourne.
Check out the Kirkey web page for dimensions on them.
Kirkey Racing - Browse Products
All that being said... I don't know if they will be ADR Legal once the new head rest is in place. But at least being aluminium there are some easy options to reinforce them or modify them.
Cheers
Michael