Seems like it's between the following choices:
1. Kawasaki 250. Make a slow bike go fast. Light bike, self-destructs less when crashed. Goes the least fast (still pretty fast). Can buy already race prepped (guess that's true of most of them). How many different races will I be able to run in on a typical weekend? (not that i'm prepared to run ANY at this point).
2. Suzuki SV-650. Has come highly recomended. Goes faster than the 250. Not sure that is really a good thing, but its an exciting thing. "Easy" to learn on? Its a V-twin and dig that. Seems like lots of classes to race it in.
3. An old 600. Most bang for the buck. 600's scream and hawl!, even old ones and are probably the most technologically advanced. Get one already set up for the track. Run Formula 40 (vintage guy, vintage bike)
4. This one is a kicker. Turn my street bike, a Ducati 1098 into a track bike. Hah! But could be done I suppose. Most people "run what ya brung". I like it and can ride it. But liter class seems a bit much to start out in. (Its a blast on the street). Its a blast on track days.

There are others. Someone suggested a Ducati 1000DS Supersport. What would that be like?

Whatever I run, it's gonna be a "learning experience" that's for sure. Whatever bike I ride is gonna be more capable than I am. But, hey, I always wanted to do this, since I bought a used 125 two smoke and a Roadracing magazine and dreamed of putting road race fairings on it and going road racing. Now I finally have the time and money.

Any sage advice out there?