So you can fly Jetstar direct to Bangkok (BKK) for $199, or $179 via Singapore thanks to this deal from samehada.
And then on limited dates in October and November you can get a cheap fare on Norwegian from BKK to Oslo (141.6 EUR), Copenhagen (162.5 EUR) or Stockholm (147.7 EUR).
So for example you can fly MEL to BKK on 9th November for $186.46. Then on the 10th fly to Oslo for $214 = $400 total.
You will need to pay extra for checked luggage of course.
The flights from MEL and from BKK are on the Boeing 787 Dreamliner which has bigger windows, less cabin noise and better cabin air pressure and humidity.
Here are some direct links for the flights to each city:
Stockholm…
http://www.norwegian.com/en/booking/flight-tickets/farecalen…
Oslo…
http://www.norwegian.com/en/booking/flight-tickets/farecalen…
Copenhagen…
http://www.norwegian.com/en/booking/flight-tickets/farecalen…
Don't have the guts to fly with a Dreamliner.