I have a bike that I bought just for track days. Its an 05 GSXR600, I got it from a guy that had raced it for 4 or 5 years and it was already set up as a track bike. Sharkskinz, everything was safety wired already, suspension was fresh, came with extra chains and sprockets, front and rear stands and it even had a nice steering damper installed. I paid less for it than I would have paid for a worn out street bike, plus all of the track-only mods were already done.
I'd be looking for somebody elses track bike, regardless of make or model. Converting a street bike to a track bike is a pain in the ass. Taking the lights and mirrors off, taping some of them up, flushing the cooling system, then take it home and un-do all of it... Fuck that noise.
Also, street riding ruins track tires and street tires don't work very well on the track. My track bike never sees the street and my street bike has never been on the track.