$274.99 USD for the cameras + $8.75 USD shipping & handling (to Perth). Add a Power Magic Pro hardwiring kit for $25 USD. This dashcam starts around $580 locally judging by a quick google. Last appearance on ozb was $550, with reports of low-mid $400s around Christmas in the comments.
From the Massdrop website:
Front & Rear Cameras
The BlackVue DR750S two-channel dash camera has your car’s surroundings covered. Mount the main camera to the front windshield to record the road ahead in full HD 1080p video at 60 frames per second. Mount the rear camera to the back car window to record the road behind in full HD video at 30 fps. The two cameras are connected with a coaxial cable and record to the same microSD card. They have image sensors for clarity in low light and a wide 139-degree view angle. The dash cam detects impacts and sudden changes in speed while driving, and also detects movement while parked. For parked mode recording, the optional Power Magic Pro hardwiring kit is required. Built-in Wi-Fi allows you to connect with the dash cam via the free BlackVue app.
Note: This drop’s base price is for the camera. At checkout, you’ll have the option to add the Power Magic Pro (+ $25).
Specs
BlackVue Dash Camera
2-channel full HD recording
Dual Sony Starvis image sensors
Cloud connectivity (supports push notifications, live tracking, and remote video backup)
Full HD 1080p video: Front 60 fps, rear 30 fps
Optimized for hotter climates up to 158º F (70º C)
HI 3559 processor (12 Mbps front, 10 Mbps rear)
Built-in Wi-Fi and GPS
Prevents up to 50 files from overwriting
BlackVue Power Magic Pro (Optional)
Enables dash cam Parking Mode
Modes: On, Off
Timer cut-off settings
Low voltage cut-off settings
Shipping
All orders will be shipped by Massdrop.
Estimated ship date is Feb 26, 2018 PT.
Keep buying cheaper separate ones, but this seems like an easy solution.