It looks like the only place to get the 16GB variant of the iMac is directly from Apple as all the stores (Officeworks, JB Hi-Fi, Good Guys, etc) have only 8gb iMacs.
The Apple store in Adelaide said it would be full price ($3099) for the 16GB, 512 GB version. The 'Genius' said I was not eligible for Education Discount as I was not a university student.
Could I still buy it online via the education store? Or is there any way I could get this version cheaper in any store?
Yes
Yes by buying online via the education store