I enjoy working with ebony, but am often reluctant to do so because it has been overharvested. To my knowledge there is no source of ebony that is certified by some organization such as the Forest Stewardship Council to have been harvested in a sustainable manner. (The issues around global warming, overharvesting , illegal logging and livelihood of indigenous people are complicated ones. Scientific American is a good starting point for more information:

http://www.sciam.com/..

I'm trying to figure out an appropriate way to deal with the other basses I sometimes sell which come with ebony fittings. Like most luthiers, I save old fingerboards and broken tailpieces to use as material for extensions, saddles, nuts, inlays, etc. For my own fingerboards I try to use quartersawn FSC certified Grenadillo or purpleheart. In this case the filler wood is from some salvaged decking material (Ipe).

In general, I feel the acoustic properties of a bass often benefit from a stiffer neck (a number of other luthiers I think have come independently to this conclusion) (Notice that I've also inlaid two carbon fiber strips in the neck, carbon fiber has a modulus of elasticity many times that of any wood. ) All of these woods are stiffer than ebony (at least in every sample I've tested) Purpleheart has the largest modulus of elasticity and the lowest specific gravity, but is perhaps not as hard as ebony. In addition you can make a fingerboard from quartersawn material (for a more stable board), while quartersawn ebony is expensive and difficult to come by.