If you are thinking of doing PHD rather than just Masters, there's chance of getting some kind of funding from the University. Well if you wanna get into some biology/chemistry school, you'll probably get some sort of funding cuz there are lots of research opportunities available on those subjects. But if its more professional degree such as Engineering or other, then chance of getting funding is less  unless u have a very good GPA and a good GRE Score.....If you have work experience for at least a year, that helps a Lot.....American believe on Experience rather than Straight Education..
Hope it helps.....