Royal Mail, along with several other postal administrations, outsourced its stand at World Stamp Show NY2016 to Herrick Stamp Co, a New York stamp dealer. While there are oodles of Star Wars stamps to be purchased, you can't buy a Machin unless it's in a prestige booklet.
It may not be Herrick's fault. La Poste (France Post) is apparently here on its own, and there are no definitives to be had there, either. Marianne, où êtes-vous?
More after I return home.