The requirement that the potential spouses must have met in person before you can apply for a fiancé visa is pretty common in most countries these days. And given some of the horror stories you hear about forced marriages, internet scams and all, I think you can understand why.

You also have to allow for the possibility you could get to Oz and find that something is wrong - he isn't who he says he is, he's broke, he's sick, he was actually hoping you'd bring him over to the US or he has a horrible mother who lives with him and will make your life a living hell.

One of you needs to make a trip to meet the other - for whatever length of time you can swing on a tourist visa (a month, maybe two). Think of it as a good faith gesture designed (if nothing else) to be able to show the immigration people that you have met face to face and eliminate that objection. Try living together for a while, with the host paying the living costs, even if it's only for a month or two. (Shows that you are capable of "supporting" each other in the financial sense and in the relationship sense.) Because it sounds like if you don't do this, you don't have a prayer of getting that visa.

And, while I know you don't want to hear this, there have been scams like this perpetuated over the Internet that have lasted five years and more. You have to be able to prove to the immigration people that this isn't one of them. (And frankly, you owe it to yourself to make sure it isn't before you do anything you can't recover from.)
Cheers,
Bev