I am an ob/gyn planning to move to NYC. I currently live in Atlanta, GA. My dad said everything was so expensive that it isn't worth moving there, but I love it! Can I afford this, and while you're at it, is an ob/gyn job an 'in-demand' job??

As long as you can afford the rent, everything else in NYC isn't so bad. (Remember you don't need a car, and all the costs associated with that.) And yes, all medical professions are quite in demand here.