Cycle trader always has lots. For 5k you can get a nice bike. I am going to be the first to say, forget about everything you learned in dirt. It doesn't matter. Only things the same are the fact they both have motors. If it is going to be your FIRST real street bike, get something that you wont cry when you drop it. It is going to suck either way, but I would rather drop a cheaper bike. Either way, you can find a really nice bike with 5k usually. If you get a 600 supersport of some kind(cbr, gsxr, etc.) remember to respect it. It will kill you fast. I haven't been riding long and I am still on my first bike actually, I am just telling you what I always heard when I started and found it to be true. My bike is a 94 Katana 600. It is my first and I got it for around 1500 bucks. It is a really nice bike actually, despite what people say. It has a more comfortable riding postion than most ss bike and being a 600, it isn't has powerful as a cbr and the likes, so that makes it a little more controllable. Don't let if fool you though. Although it is one of the 'slower' bikes, it still runs 12 sec 1/4 mile and handles good, I still haven't even got to push it to its limits yet but will soon. Regardless of what you do, keep the shiney side up.
This isn't a pic of my bike but one I found on the net. It is still a katana just like mine though. I really recommend these as a first bike. A lot more powerful than a 250 or 500 but still not as touchy as a ss600 bike.