As above. Frankly, $600 is enough to get you started. No, it's not tight. It's tight if you want to buy an F100 or an EOS1v, or even an F80 or EOS30. But you really don't need any of those cameras to start out. Nice to have, but not essential by any stretch of the imagination. It's a bit like learning to drive. You don't need a new car, and you don't need a 1.6l saloon to learn to drive, nor a 3.0l beemer. Nice, but not the end of the world certainly if you don't.
Price of camera has no direct correlation to the worth of the pictures it produces. Sad to say. Over here where I am, when the average person talks about using cheap, no name equipment like lenses, they mean cheap, no name lenses. Not Sigma, Tokina and Tamron. Stuff you would never even have heard of. A lot of the people I know are lucky if they get a modern camera from a current line. Far more usual are the Canon F1s, Nikon FMs, Olympus OM10s. Occasionally the Pentax MZ50, the Canon EOS 500n, the Nikon F60. And the fact is, a lot (but not all) of these people take excellent pictures.
There are two main points I am trying to get across. One is that the camera is just a tool, and the most important part of the picture taking process is you. Learn to forget the bells and whistles, and start to see. Second, modern technology has made it such that the average $400 camera now has more bells and whistles than even the best cameras from 10 years ago. I'd like to think they were taking brilliant photos 10 years ago.
You're better off catering wisely with your $600 than just buying the best there is out there for that price. For starters, as a photographer you will better appreciate having a good camera bag, a decent tripod and a cable release. That will knock off more than you imagine, and a lot of people skimp on this section or completely forget to take it into account. Don't. And if you're new to the photo industry, these cost more than you think they will.
And don't forget film either. I know of some photographers who will throw $1500 at a new lens, but balk at spending $$$ on film and processing. You will be a FAR better photographer with a $200 lens, and $1500 of film costs, than vice versa. The above also applies for camera bodies. However, I do admit that you will have a far newer and more fancy camera outfit to admire if you go the other way.
I can't recommend anything specific, but IMO searching for a good second hand deal is an excellent way to go. Preferably have someone who knows something about cameras give you a hand, otherwise you have to be very careful. Otherwise you have to be cautious because as with any second hand business there are a lot of sharks out there.
Good luck!