Oh, ok. Thanks guys for the info - upon doing research myself back around the time I posted this, I discovered that I'd probably not be able to afford the fees anyway - even with support, it is still expensive and I don't want to ask for help from my parents or anything.
Looks like I'm sticking here in Australia for now and maybe I'll do post grad study there as you said, hopefully I can build up some money through some sort of part time or casual work.
They actually pay you to do graduate studies, not that much though, and I don't think it applies for international students, so you would probably need to get a scolarship, not to cover tuition fees, but to cover living expenses, unless you already have enough money to live off for 5 years.
Getting into MIT for undergraduate studies is probably really hard, you are more likely to get in at graduate school. Aim to be the 1st or 2nd highest rank in your undergraduate studies in physics at a Group of 8 uni and you might be able to make the scolarship. Oh, also you definently need to do honours.
Have a look at piled higher and deeper comics to see what life might be like as a doctoral student in USA, and also for a bit of a laugh
I've heard the comics are surprisingly accurate at times.
Good luck