7 day MetroCard (US$27) * 2 = US$54 ~ 55
http://www.mta.info/metrocard/mcgtreng.h…
Budget for Food (US$100/day * 7) * 2 = US$1400 ~1500
http://411newyork.org/guide/2007/04/10/b…
Airport to/from Hotel (Free if hotel has shuttle to US$60)
http://411newyork.org/guide/2008/01/27/n…
US$2500 should be more than enough but keep an eye on your spending.
So far, 60% of the US$2500 has be used for necessities and you haven't even started to shop yet and some attractions may charge an admission fee to get in which will slowly eat your funds away.
Free and/or Cheap in NY
http://www.freenyc.net (Events)
http://www.nycgo.com/restaurantweek (Restaurant)
http://gonyc.about.com/cs/museums/a/muse… (Museums)
http://411newyork.org/guide/2007/06/18/t… (Discount Passes)