If you are wanting a board in ebony or rosewood (wouldn't work for lighter coloured boards) you can make your own by cutting two strips off either side of the board before slotting the blank then gluing them back on once the board's tapered. Just make sure you glue the strip back onto the side it was cut from, that way any grain feature is closely matched. I'm doing a couple of boards like this at the moment.
Strips & slots cut (I usually just put some witness marks on to make sure I can't get the strips on the wrong side or wrong way around)

Fingerboard radiused ready for fretting

& finally with the frets just put in

I got this method from a comment Micheal Collins made in his excellent DVD series on building Selmer Maccaferri's. He used to do it this way but he too, get's Bob Garrish to do his now.