How I can get a GSM SIM card in US, during a week visit?

I'm traveling end of august for 1.5 weeks to NYC from outside of US. I want to have a valid GSM SIM Card that works on my factory unlocked iphone, and be able to use data and a few minutes so I can move in NYC and waste lest time moving to places using the GPS and also finding places near me.

So I would like to k now about cheap options

Net10 will be really cheap. Buy a Net10 SIM from any store and activate the SIM and refill with the amount of your choice, for $20 you'll get 200 minutes on Pay As You Go and so on. If your budget is around $45, you can't go wrong with StraightTalk, unlimited everything for $45.