When we were in Australia in 2012.  We purchased 8 standard 12V batteries from Batteries Direct (info@...).  The pricing seemed good; they were able to provide batteries from the USA (the Australian manufactured batteries didn’t match the size); they delivered the batteries to our boat at a marina in Maloolaba.  We have been pleased with the batteries performance.  I don’t know if they sell the golf cart batteries you are looking for.