How many frequent flyer miles are needed to fly business class from NYC to Australia?

This depends greatly on:

1. The time of year you travel

2. The airline you use

3. Where in Australia you are travelling

4. How many stops/plane changes you are prepared to make

February 1st - Feb 21st using Delta travelling JFK - LAX- Sydney round trip is 305,000 Frequent Flyer miles.

Using the same dates and United airlines travelling Newark - Honolulu - Guam -Cairns and then back via Guam, Honolulu and Houston can be done for 150,000 FF miles - a massive improvement but longer flights and more stops.