I recently enjoyed my 5th anniversery with my 8 string 31 fret bocate Europa, and it's gotton even better sounding with time. I see they already gave you info on it, and I can tell you it's indescribably awesome.
There is no doubt in my mind that they can do an awesome 9 string with 36 frets for you, should you desire. I considered up to a 10 string with 40 frets for my project, but decided to stick with my original concept of 8 strings with 31 frets -which has the same range as a 7 string with 36 frets.
If you DO decide to commission such a bass, I STRONGLY recommend (aside from thinking EVERYTHING through very thoroughly and carefully in great detail) that you consider getting ebony laminates in the neck... they contribute to an utterly earth-shaking sound that can't be matched by anything else. Other Alembic owners with ebony laminates will back me up on this.
My custom 8 strings of power -featured custom, June '99- has an awesome 13 piece neck. The outer laminates are flame maple (and also the same pieces of wood as the body itself, a really cool and striking feature) and there are two pieces of rock maple, and then between these 4 maple lams are 3 purpleheart lams sandwiched between 3 pairs of ebony laminates. This produces a tone and sustain that has to be heard to be believed, and which is the most awesome bass sound I've ever heard. I lean towards thinking that only another Alembic with similar laminate choices could rival it.
I recommend doing some research and strongly considering this when the time comes...
You wouldn't regret it!
Good luck with your project!
And of course, I give this bass and Alembic the highest possible recommendation! It really doesn't get any better.
P.S. also think about whether or not you want 2 pickups... a large part of why I elected to go with the 8 with 31 frets instead of with the 7 with 36, was that, after seeing one of Conklins' Sidewinders, it became clear that it would be challenging to pointless to have 2 pickups with 36 frets, as -if they COULD fit, they'd be right next to each other and would probably have little difference. I had them give me 26 full frets and then 5 more partial frets on the high strings (which work great) so that the neck pickup is just pushed out of the way a little on the treble side, causing it to be slanted. It has a great sound, and both pickups have essentially the normal bridge and neck pickup sounds. If you go through with 36 frets, you'd likely have to or want to sacrifice one of your pickups. Maybe you're okay with this, and maybe you're not.
Again, good luck, hope to see your custom featured as their first 9 string!!!