Find your local track day org and join their forum. Get to know some local track day riders and racers. They usually have a classified section with track bikes of all displacements for sale. Many have all the track bits on them already, and they are usually reasonably priced. I bought a couple of track bikes that way, and met riders that became friends. Edit to add: I second the SV650, kwak 300/400/650, Yam fz7. Your learning curve will be faster on a smaller displacement bike.