In the winter, when the air is cold and the snow is fresh, Jim Smith, managing principal for Kensington Realty Advisors, starts to hear the call of the wild. It makes him pull out the ski equipment, call up old friends, grab his wallet and head to remote mountain peaks in faraway places like Mica Heli Guides. Because for ski bums with money, there’s no better way to satisfy winter’s call than a week of heliskiing, snow’s most exclusive, most expensive sport.