Is this your first bike? If so, I strongly recommend getting a Suzuki SV650S. The new ones come fully faired and some you can get with ABS.
It's a very light and nimble machine, easy to throw around. If you take the MSF Basic Ridercourse (which you should), it'll be a perfect transition from the little trainers they ride you around on, but it'll have a whole lot more torque.
Now I will say that they don't have the top-end of SUPERsport motorcycles, but you don't want to be one of those d!ckholes that are splitting lanes down the highway at 160MPH anyway. It pulls hard till about 8KRPM and then starts to fall off, being a V-twin. PLENTY of torque for the twisty back-roads and nice low-end for driving around town.
My recommendation would be to find one slightly used for like 5 grand, ride it for a year, REALLY learn to beat the hell out of it, then if you find yourself having a "need for speed", sell it (used, there is a HUGE market for them!) and get yourself a supersport next season.
And wear a helmet!! And leathers or poly/mesh if you can. Road rash hurts!
As for where to look, Craigslist has a huge selection of used bikes. Don't buy new...you WILL at least tip your bike over once and if you buy something new and scuff it all up, you WILL be pissed off.
Don't be afraid to ask questions...why is he selling it, did he ever race it, did he ever crash it, etc.
Plastics can be replaced pretty easily. Check for scratching and scuffs on places that aren't as easy to replace...handlebar ends, footpegs, frame pieces, engine cases...random directional scratches usually is a tip-over. Long parallel streaking scrapes means it was sliding. Dings WAY up on the tank or tail section can mean it was flipped/highsided somehow.
Make sure it's in general working order...good oil level, no leaks, rolls smooth...have him start it and run it to temp. Make sure the sprocket teeth are straight and the chain looks good. Check the brakes for firm feel and stoppage, that the throttle returns, etc. You can tell when a machine is in good shape.