"(it was only last year the government of Australia asked Defence for a backup plan for the JSF if it was late, You'd think Defence would have at least asked around re price/availability from various manufacturers etc!!)."
And what's to say they didn't?
I know they did not go through the "massive
PR blitz/press conferences with chest-beating, self-flaggellation, ashes & sackcloth-type very public angst/recriminations/everybody get their two-pence worth in" kind of freak show that so many expect with any procurement decision, but why should they?
I expect that they quietly called up each applicable manufacturer of suitable aircraft (Lock-Mart for F-16F, Boeing for F/A-18F & F-15E, EADS for Typhoon [is there a two-seat attack-oriented version... I think not], Dassault for Rafale [see Typhoon comments]... I doubt they even bothered with Sukhoi), asked them "If we ordered 24, when could we get them and for how much (with 15 years support & operations included)" and reported the results to the Defense Chief along with their assessment of relative performance (lots of real-world data is available without a formal competition).
The Defense Chief then talked to the RAAF senior staff, then he made his decision and contacted the PM, etc.