Hypothetically of course ... if an ACF was re-established I think opposition to it would be muted in light of the recent PLA(N) deployment, because that deployment won't be the last one in our region. So it would have populist support and the Opposition can bark away but it will have little impact at the end of the day.
As for the cost ... perhaps lease the aircraft (like we intended to do with the F-16's originally). Hence why some advocate for utilising second-hand aircraft for the initial training and learning period. No CapEx, no depreciation and no capital charge! Sure the long term goal would be to buy something advanced and fit-for-purpose.
Another option could be simply leasing or purchasing a training/light combat type like the FA-50 or M-346 (something proven and in service). But again in light of the recent PLA(N) deployment it might now be regarded as not good enough (or survivable enough) ... but there would still be a need for a LIFT type anyway.
LIFT and/or leasing a combat type should be achieveable within an "up to" 2% gdp budget.
The biggest problem may be getting enough pilots in those intitial first few years, either new or existing transferring from other types, creating gaps in the other operational squadrons. But perhaps that could be alleviated by enticing experienced pilots back to fill those operational gaps?
Training could be provided by external providers and their knowledge would be invaluble.
Look I know, this could be "fantasy" and I appreciate the alternative points other people have made here recently that it could wiser to simply invest further in existing platforms (and with supplementary unmanned capabilities). I don't think there are right or wrong views, it is always good to read other people's thoughts and especially when they take the time to put a lot of thought into it.
Another area to explore, I think Aussie Digger brought it up last year or so, was whether to acquire EW/emission killing capabilities (like Growler or another type). Then perhaps let that complement the P-8's which could carry the ship-killing muntions. If so, fantasy or a practical and affordable alternative to take the fight to (i.e. deter) a powerful adversary operating in our region?