In case you don't work for a school/uni and therefore can't get the free copy that was recently highlighted here (https://www.ozbargain.com.au/node/214357), or don't work for an employer participating in the HUP (https://www.ozbargain.com.au/node/214028) - there is at least a 50% off offer on! :)
It is designed for those currently running Office 2010 who have recently upgraded to Windows 10
1) Install the Get Office app from the Windows App store (https://www.microsoft.com/en-au/store/apps/get-office/9wzdnc...)
2) Run the app (you might need to close it and reopen it to get the deal to appear) - you should see a link that says 'You don't have the latest version of Office. Upgrade today and save 50%'
3) Click 'UPGRADE NOW' to open the purchase link in your web browser
4) Assuming you want the better value 5-licence version (Office 365 Home rather than Office 365 Personal that it defaults to), click on 'Continue shopping' to the right of where it says 'Cart', then add the Home version to your cart [ http://www.microsoftstore.com/store/msaus/en_AU/pdp/Office-3... is the product page]
5) Reapply the personalised discount code at the checkout (the app prefilled this bit for you) and then remove Office 365 Personal from your basket
6) Complete your purchase and enjoy the 50% discount!
IMPORTANT NOTE - I found the app kept taking me to the UK website rather than the AU one (I used to be in the UK, my account is still set for that) - I couldn't get them to sort it via Live Chat so they told me to call instead. The phone team (1800 267 785) were very helpful, confirmed my account details and processed the whole order manually. To be honest if you have any problems with the above I'd say you're as good just going down this route! Just tell them you received the 50% off offer in the app and couldn't get it to go through and they should be able to sort it for you.