If you're a new rider i recommend getting as much training as possible...especially considering you're in NYC, motorists just aren't cognizant of how to share the roads with bike's, especially taxi's. I suggest starting with a Kawasaki Ninja 500R (~$5K - 50+MPG)...more power than a beginner 250 and enough power delivery to keep you satisfied.

Lot's of good deals to be had as dealers need to make room for new models. I was recently offered $6K for a new 2008 supersport Ninja ZX 6R $4K below MSRP. Happy hunting...