If you have time in Oz, a simple multi segment run can earn you the needed four QF

squiggles inexpensively (at least much less than £1000).
Also, have a look at "Any Seat" Awards - a SYD-xMEL-HBA vv economy¹ journey can be had for 24,000 QFF points and AUD140 (will earn 4

, 40 SC and 4000 QFF points)
¹
FWIW, a SYD-xMEL-HBA vv Business Class journey can be had for 48,000 QFF points and AUD190 (will earn 4
, 160 SC and 5000 QFF points)