As you're in Melbourne, if it was me - I'd go to Beninca Motors in Surrey Hills and purchase one from them, they were the original Autronic distributors and worked with Richard Aubert as he was developing Autronic.
They also have a very very good (and proven!) reputation for their tuning capabilities and know the Autronic systems and software back-to-front, so you will, more importantly, have their support in making sure you get the most out of your ECU and setup when it comes time to tune it if you choose to use them.
All of my experiences with them have been more than positive - I trust them completely with my car and they have always ensured they put the reliability and driveability of the setup before big power numbers when it's on the rollers.