Best Professional SLR Digital Cameras

Im young but i want to start early on my career as a photographer and that means i want a good camera. I already have a digital camera and a 35mm SLR. I want a DSLR but is this the right one for me.

I am a photography student and am only intered in good digital SLR, like the nikon D200 or 300, or maybe even the B40. Are there any duty free stores at LAX airportthat sell these kinds of cameras? Or something equilivant? I need to findout in advance, i will be at the airport for 10 hours