Thirteen-year-old Joshua Nussbaum of Bloomfield Hills became a full-fledged consumer Saturday upon the event of his Bar Mitzvah, the traditional Jewish ceremony and subsequent extravagant catered affair that marks a boy's passage into materialism. 'From this day forth, I shall acquire wealth and goods in the venerated tradition of my fathers,' Nussbaum said during the five-hour, $18,000 reception, which featured a live band, a professional balloon-animal artist, and a video retrospective of his life on a big-screen TV purchased for the occasion. Added Nussbaum, who collected more than $21,000 in Bar Mitzvah gifts and cash: 'Today, I am a consumer.' 