It depends in what state you purchase the vehicle and that state's laws. You mentioned New York and according to the New York State Department of Motor Vehicles (DMV) they recognize your foreign driver license if you remain a resident of the nation that issued your license. You do not ned to have a New York State (NYS) driver's license to drive in NYS unless you become a resident of NYS.

It is more complicated since you will need to register and insure the vehicle which you are purchasing. If you are going to be in the United States for over 30 days it might be necessary to obtain a U.S. driver's license since most insurance companies will require a valid U.S. license after that time period. You should be able to find an insurance company that will allow you to purchase a policy with your international permit as long as you are in the process of getting a U.S. License. The cost of insurance will vary depending on the type of vehicle and other variables.

It would be wise to discuss your options with the car dealership that you are buying the car from as well as possibly a travel club such as AAA in the U.S. since they are likely to have dealt with this situation in the past.