Thanks dude.
The entire Double Din kit which includes the AC control panel cost 350USD. I ordered it from the US.
These kits can be hard to source these days but check the g35driver forums, some of the vendors recently got more stock.
You can also buy a dirt cheaper non oem Metra version for like half the price (but it looks like ass).
PAC ROEM-NIS2 unit which is required for BOSE systems cost 40AUD, bought off amazon.
Basically lets the headunit work with factory Bose system.
Axxess ASWC-1 unit for steering wheel controls cost 60USD, also off amazon.
The headunit itself was 600USD, bought it off some US site.
So i guess in total it cost around a grand.
The headunit/doubledin kit with fit both bose and non bose systems. i would say the only difference might be the wiring harness.
But if you follow the chart i posted you can use a test light to probe a few of the pins on your harness and work out if its the same or not.
Dual aircon shouldnt makes a different between the cars. Basically if you have dual aircon, the panel will have a button soldered on for you. If you dont, they dont put on this button. My car has dual zone aircon, but the AC Panel i bought doesnt have the button.