You can buy anything online. Buy want about a car. Would you trust your judgment and pull the trigger on a car purchase simply by looking at a picture on a screen?
The Australian focus on sports models and only let you configure a WRX or a BRZ. However, the US site allows you to see the complete line of models from the WRX to the BRZ with the Outback and the Subaru XV Crosstrek. Here’s the screenshot of Build Your Own 2015 WRX STI.
Off hand, it appears that Subaru’s online offering is way behind other international brands have been able to put on display. The BMW configurator for instance is well integrated, sharp and with a live 360 degree view.
As for used subies, there are plenty of local dealers that have string online presence. Even back in 2011, as I was shopping for a pre-owned Outback, all the pre-sale discovery was done online on dealer’s websites and on aggregators.