Michelle Obama’s footwear is causing a fashion frenzy, after the former first lady sported sparkling $4,000 designer boots. The “Becoming” author stepped out in the eye-catching pair of Balenciaga boots on Wednesday at a Brooklyn stop on her nationwide book tour. Former “Sex and the City” star and fashion designer Sarah Jessica Parker served as the celebrity guest moderator for the chat about Obama’s best-selling memoir. The gold, thigh-high boots retail for $3,800, and several sizes were sold out or low in stock on at least one site selling them after Obama's appearance. Multiple fashion gurus and first lady watchers...