Broad Street Partners LLC, a real estate development and investment company that specializes in multifamily condos and aparments, purchased the 323-unit Station Nine apartment building in Durham. The $47 million price tag made the deal the largest per unit price, $145,511 per unit, in the Triangle Region, according to CB Richard Ellis. Wood Partners, a national multifamily developer, sold the property that had only just finished construction in April of last year.