Myself, I'm happy to buy 'off the rack', not to mention there's usually a barely used ALEMBIC that someone bought and realized they were in over their head and the old PBass wasn't so bad after all . . . plus he ate the depreciation and I can get a good deal on it.
From my time spent around various builders, I can tell you that there are custom instruments and there are CUSTOM INSTRUMENTS. Let me explain:
Custom instruments are the equivalent of ordering wheat toast instead of white toast with your breakfast at Denny's. You want a different color, a slightly different wiring/pickup layout, different frets. But basically what you've asked for has ALREADY BEEN DONE quite a few times and the builder sees this as just one more time. For instance, an EXCEL with Jazz pickups and an inline headstock.
CUSTOM INSTRUMENTS are another animal, because now you are boldly going where no customer has gone before. New template. Wiring/pickup layout that would boggle the phone company's techs. Really specific wood/figure from the land of UnObtainium. Stainless steel ukelele frets. You can see where I'm going with this: It just takes a lot of time to order EVERYTHING 'off the menu'. You are ordering an extremely personalized instrument with naturally no regard to the builder's shop routine, parts ordering, production schedules, etc.
And these problems often make it impossible to reasonably accomodate a customer who just expects these things to hatch perfectly in short order. This kind of thing is in no ways limited to ALEMBIC: When I worked at Gibson, a world-famous guitar hero refused and sent back six Custom Shop Flame Top Les Pauls made especially for him at his request (all six to die for, would have sold for 25 grand each at Gruhn's) because the bodies were ONE-EIGHTH of an inch too thick!
IF I were in a position to order an ALEMBIC just for me, I wouldn't care how long it took once Mica or Susan gave me the straight of the schedule. Art can't be rushed, and there's just a LOT more to life than agonizing about the grain of this or that piece of wood, or how much longer is this gonna take. I'd simply trust them to do their magic one more time, and I would be a little careful about nagging the magician about just when is that rabbit coming out of the hat!
J o e y