I happened across a Mandarin-oriented bookstore in San Francisco this weekend... Sodoyo is on upper Powell St., right across from Washington Square Park. They sell video, audio, books and magazines. Prices are very, very low... I picked up a bunch of DVDs of pre-1950s films at less than $2 each, photo guidebooks at about $6, a paperbound atlas of China for about $4, textbooks at a third of what they might cost elsewhere. The feel is like Kinokuniya in Nihonmachi, although not as extensive (and not as expensive).
The films I've viewed so far are in Mandarin, without any subtitles or alternate audio tracks. They carried a couple of lines of classic film, though. Lines of stock weren't complete... it felt a bit like overstocks, although I suspect the business is more complex than that. There's little English in the shop. Red labels are list price; white labels show the 20% discount for members.