Found this in the back page of the Big W catalogue Nov 2-8. Not sure if the phone is locked to the Optus network, other OzBargainers may be able to shed some light on this. Seems like a great deal nonetheless for a decent phone.
Edit: since the deal is now active, the link to the website is now available with the stated price (and delivery option)
Thanks OP. Other options: $379 at Officeworks if you can find stock. Also available for $399 at Optus.