I bought one of these (Century 55D23L) for $162.75 at Bursons.
Century are Australian Made and apparently "for Australian climate conditions" - that's their marketing blurb...
Supercheap Auto quoted $160
Autobarn $159
Battery World $159
If you are a frequent starter like me and want the battery to last longer, go for a 75D23L it has a higher rated CCA and longer reserve capacity. However I don't plan to have the car for another 3 years, so a 55D23L will suit my needs...
Supercheap Auto quoted $199
Battery World $199
Bursons $180.10
Autobarn $189