Hello there - welcome to New York! I live in the area and occasionally look around New York City as well, but mostly during specific festivals.

The one retail location I can wholeheartedly recommend is Beads of Paradise in downtown Manhattan. They have a wonderfully eclectic selection of things to look at. A fair number of African trade beads, and lots more besides. But just one of the world's great bead stores. Also - check out the Ruben Museum right down the street -- a must visit for any fan of Himalayan art! The Met, of course, also has a few nice little trinkets.

Otherwise, there are many antique galleries in New York, but none that I'm aware of any that specialize in beads. Interested to hear whether others have had better experiences!

Cheers,
Abe @ Beadstore.com