Duty-free Shops in New York
New York City
Of course, in the airports when you leave the country, there are duty-free shops. Presumably, articles such as alcohol and perfume should be cheaper because they are not subject to the Federal Excise Tax on alcohol, and you do not have to pay New York sales taxes of 8.25%.
There are other shops in New York which can arrange for delivery of products directly to your airplane so as to avoid New York Sale Tax.