Where can you buy?
Best to go to Batch Brewing in Sydenham Road, Marrickville to get it fresh.
Failing that, most of the "Craft Pubs"* in the city & near surrounds would have a Batch Brew on tap from time to time. Download the "Now Tapped" app & you can see what venues have what beer on tap.
Barneys Wines and Spirits in Botany Road, and Camperdown Cellers on Parramatta Road usually have a good selection of Batch Brews in bombers.
Go to http://www.batchbrewingco.com.au/. They list places where they have delivered recently.
* Keg & Brew, Bitter Phew, Dove & Olive. Pumphouse, Quarrymans, Sweeneys, Beer Deluxe, Local Taphouse, Harts, The Henson, The FLodge, Duke of Gloucester, Petersham Bowlo etc.