When we bought our PS3 in Japan, we stopped off at an electronics shop in Narita airport on the way home and an extremely helpful lady found us the correct convertor for UK voltage.
Presumably because it was at the airport, she had a very useful folder detailing voltage and wattage for just about every country in the world, and by comparing this with what was on the boxes, she located exactly what we needed. It's been working happily for two years now, and although it's hardly an attractive piece of equipment, we've had no trouble with it at all.
You might like to try one of the larger electronics stores wherever you're going on a weekday (weekends, particularly in places like Yodobashi Akiba can get incredibly busy) and ask for a Japanese - Australian converter. You're likely to find they have the same information to hand, and are just as helpful. I particularly liked the chaps on the tax-free desk there, as their English (particularly their grasp of technology-lingo) was excellent. Turns out one of them had worked in the UK for over six years
Failing that there's always Narita airport's electronics shops
