That's ~8 used EV batteries. Each cost less than 10k, maybe 6-8k AUD.

If you know your way around high voltage DC, got a tractor and appropriate emulator - not exactly difficult or super expensive to pull off.

Granted it's pretty uncommon setup as grid batteries themselves are pretty cheap too and used EV battery is simply too large for home user, too much hassle, liability, etc to save like $2-3k.