I've had a tub/shower door assembly on order from Kohler for about three months now. I knew when I ordered it that it was not in stock at the factory, but the factory's anticipated delivery date now has been postponed three times, each time 3-4 weeks. Very annoying. I could have gone with a custom set of doors (any that I liked were 3x more or greater, though), but decided I liked and could live with the semi-custom Kohler door.
Is this normal for them? Now, if it was a Japanese company, they could tell you not only when they could supply it, but probably the day and hour it would be built.