I'd wait to buy a bike until I moved. That way you can build a relationship with a LBS where you're moving to, rather than moving from. Of course if it were me, and I was going to be riding a lot in a major city, I'd buy used. Get an old mountain bike and make it a single speed, or not. Then wrap the hell out of it in used tubes and duct tape. I doubt that a new shiny bike would last long in the big apple.

Do they still call it the big apple?