Roger Gastman has worked with Bansky and Shepard Fairey. You have not. How a punk rock kid became the world’s expert in graffiti and street art. If you still think graffiti is just kids defiling your neighborhood, you need to get with the times. Graffiti, and its sibling, “street art,” have infiltrated high-end galleries, museums, and private collections, with top artists’ work selling for five-to-six figures. Roger Gastman is the man behind a lot of that evolution. As a maga