metcalve 
I suggest that you make use of the new T-Bus (orange and stands out!) service that operates between the Domestic and International Terminals at Brisbane Airport.
The service operates on a daily basis between the hours of 05:10L & 22:50L. Am not privy to the frequencies/schedules, however you are able to view the timings on signage outside the Domestic terminal. You are able to board the service outside the QF and DJ arrivals hall and the cost is $5.00.
Certainly a nice alternative to a Taxi!
Inter-terminal transfers on the Airtrain cost $4.00.
Cheers