If it's any consolation, I think it was about $1k to ship the motorcycle from BNE to CNS when we moved up. That said, it was via a specialist company who made sure it was properly strapped down, etc. With the car transport, I'm pretty sure that you can't have anythign at all in the cars when you transport them, not even anything in the boot.
I'd be a little wary about driving a brand new second-hand car that far without at least a few weeks to hunt around town in it. It could cost you way more than $600 is something major were to let go half way between TSV and MAC. Goodness, you may even end up having to stay in *gasp* Bowen - it's just not worth contemplating. Let me know if you do go that way - I can probably be talked into buying a new/second hand 4WD from Bris - you could drive the 121 down, and whatever I buy back up. NB - I'm cheap, so whatever I buy probably won't have cruise or AC.
I've always found second hand cars to be ridiculously priced up here (except, of course, when I try to sell them), and we've bought both our cars from Bris and saved buckets. Not to say great deals aren't available, I'm just surprised that it's not cheaper for you to fly down and buy her a car down there. There's a lot more people down there, and a lot more sellers, so you get a better range and more competition. Again, the obvious exception is if you're trying to buy a car that I'm selling - I can't seem to give them away.
Good luck,
Matto