Get the MechPro 12V Battery Charger 2700mA at 50% off or $21.99 at Repco. Offer will be available in store until the 18th of May. Be sure to read the Charger Manual carefully before you start using it though, because I’ve seen a few people mess up their car batteries before.
I couldn’t find the exact same charger anywhere else, but did see the Projecta 12V Battery Charger 2700mA for $32.95 at Autoparts Specialists and for $74.99 at Supercheap Auto, excl. delivery charges.