The Nederlander Organization reportedly has acquired the Biltmore Theater, one of the last classic Broadway houses to have been independently owned.Neither James M. Nederlander, president of the company, nor his son, James Jr., returned calls. But reliable industry and bank sources insisted that Nederlander had purchased the 950-seat house on West 47th Street and was seeking extraordinary concessions from various Broadway unions to make the theater economically viable. One source familiar with the Biltmore’s recent history estimated a purchase price of $ 1 million to $ 1.25 million, far below both the $ 5 million once demanded by its most recent owner, Samuel Pfeiffer. The Biltmore, built in 1925 and home to such hits as Neil Simon’s “Barefoot in the Park” and the ’60s rock musical “Hair,” has been dark for more than six years. During that time, it has become an eyesore, suffering considerable damage by fire, vandalism and neglect. Jack Goldstein, a prominent theater preservationist, said Thursday that the cost of renovating the theater could be in the $ 2.5 million to $ 3 million range. The Biltmore’s interior is landmarked, he said, but it is not a particularly complex interior, while the exterior is not landmarked. Still, the move prompted considerable head-scratching in Broadway offices Thursday. The Biltmore has a 520-seat orchestra, comparable to a number of other houses that are difficult to book.