Cheapest I've seen soo far.
Conveniently charge two GoPro batteries simultaneously with this dual battery charger and spare 1220mAh lithium ion battery for your GoPro. It charges via most USB ports. For up to 38% faster charging, use it with the optional GoPro Supercharger (international dual port charger). Dual LED indicator lights display the charging status. You can also charge your spare batteries while you use your camera.
Key Features
Can be used to charge 2 GoPro batteries simultaneously
Highly versatile, it can be used with most USB ports
Dual LED lights indicate charging status of both batteries
Compatible with HERO6, HERO7, and HERO8 (not included)
That's a fantastic price for official gear.
HOWEVER, consider looking at the cheaper stuff available on Ebay.com.au if you're happy with third party gear (Wasabi has a 3 year warranty for example and $60 should get you 2 batteries plus a charger).