"With a total project value of $2.7 billion and a capacity of...

"With a total project value of $2.7 billion and a capacity of 2.0 GW / 4.2 GWh"

https://www.energy.gov.au/news-media/news/arena-backs-8-grid-scale-batteries-worth-27-billion

So $2.7 BILLION for just 4.2GWh

Australia's annual energy consumption is around 200TWh

yep, those batteries are going to be real cheap ... using some technology that doesn't even exist maybe but certainly not with current battery tech

And for those who want to point to all the great battery technologies in development, there's been all sorts of great looking things in development for a decade, none of them have proven viable yet