Sending your beats blindly to labels probably will not get you very far, if anything you risk gettin your music jacked. Think how many people bomabrd them with cd's of there work, daily...
Right now it's really more about you gotta know somebody to be somebody.
The more people you know, the bigger your network & your stuff can get passed around to a larger number of movers & shakers.
And I agree with above dude, rep your current scene, if you can make it happen in AUS & blow up there, it will be easier for you to break in over in the US, which is like he said, saturated.
Everybody & there mama is makin beats, mixtapes or something now, so it's really hard to filter thru the noise, even if you are better than some of these big time dudes.
AUS loves hip hop & the scene there is large from what I understand.
Make a few beat CD's or "mixtape style" compilations of your beats.
Get them out there, local shops, mail order, magazines, online, websites, etc...
if you're good you may get noticed.
Take any feedback & polish up your work to get it to a level where they're knockin your door.
Once your a bit more established & if you are super serious, you can always finance your own project, i.e. pay an MC to appear on your project.
You be surpised how many large, legendary dudes are available for freelance vocal work.
Ranging anywhere from 1,500-10,000.
Sounds pricey but it could be a surefire way to get your project into the hands of a larger distributor in the US or label even.
I know some dudes making paper $$$, blowing up right now & the truth is, they are mediocre producers at best.
But they got the industry hustle down & know a lot of people.
I'm talking dudes who less than 5yrs ago were not even remotely interested in making music, all of a sudden they're DJ's & Producers...
People are coming out the woodwork these days.