Agree with Icarus, and I think this will be the compromise.
Nice airside luxury coach transfer (rather than ex public transport busses) with a nice comfortable departure lounge in T3 (rather than bus stop on street), Perhaps $5mil to set up. QF international checkin at T3 as well for Perth originators. There is no way duty free stores or other shops/cafes are going to set up in T3 for just a few flights per day, it's a ghost town as it is and most existing shops have gone bust since Virgin left.