This is a good deal if you are after a Google Home and a portable battery for it.
The 10% cashback from Cashrewards and various discounts for David Jones gift cards (e.g. 10% off at Entertainmentbook) will reduce the purchase price.
The Loft battery is $69.95 at JB HiFi ($79.95 at David Jones).
Description of battery from manufacturer's site
LOFT is a portable battery base for the Google Home that let's you unplug and take Google anywhere you choose. The powerful lithium-ion rechargeable battery provides up to 8 unplugged hours of use. Simply detach the Google Home base and attach LOFT, and you've got cord-free mobility at home. 4 LED lights on the front of LOFT indicate the remaining battery life before needing another charge.
If you're after the Google Home itself and dont really need the Loft Battery, consider this deal: $129 delivered from Google, and you get YouTube Music Premium until April for free: https://www.ozbargain.com.au/node/416929
I personally think that having the Loft Battery base would be darn useful though.