I happily purchase niche links in vendor directories (both online and print) for one of my clients, because they send traffic and I can directly attribute sales to them. I haven't looked; I suspect the links are not nofollowed, but I don't really care one way or the other, because they send *traffic.*
But unfortunately, it doesn't look like Google feels the same about it. The primary directory I've used was most likely hit by the first Panda and never fully recovered (they probably don't know to this day what hit them) But they're still an industry directory that my client's customers use, so they still send us traffic. Just less than they used to.