Originally Posted by
skr00zloose
...you never know, you might get lucky i guess.

look around long enough and talk to enough people and you may come across a screaming deal. i do it all the time

Yeah, but you like to work on them!!!
My advice is that yes, you can find a $600 dollar bike. I recommend getting a shop manual and some good tools. The good thing is that with a $600 bike, you will get to learn how to work on the bike...or find someone who can work on it cheap.
I agree with the others, save some more money and get something in better shape. I know it will be tough, but it will work out better in the long run.