Given that HMAS Melbourne decommissioned in 1982 and that in 1983 the Australian Government announced she would not be replaced, I'd suggest that "interest" was at best wishful thinking. Particularly during Typhoon development......
"Massive cost" can be a very subjective term.
Straight from the last MPR report, the biggest Air and Maritime projects (Land not included as equipment costs tend to be much lower cf manpower) :
A400M - £2.7Bn
Typhoon - £18Bn
FSTA - £11.4Bn
Marshall - £1.8Bn
Total - ~£34Bn
F35 (a "joint" asset) - £5Bn (yes it'll be a much higher figure eventually)
QEC - £6.2Bn
T26 - not published in MPR but statements indicate £8Bn
T45 - £6Bn
Astute - £9.6Bn
MARS - £0.5Bn
Total ~ £35Bn
QEC doesn't even make fourth on the list. QEC + F35 is about 16% of the combined total. Typhoon on its own is 26%.
A very simplistic analysis admittedly and doesn't include the monster that is Successor among other things. Spreading that spend out over time would also be very instructive.