Ti is stiffness challenged. You won't get a reasonably stiff Ti fork unless it's seriously oversized relative to a carbon or aluminum fork. And at that point you lose big in terms of aerodynamics and cost. Remember, Ti is about half as stiff as steel. The main way to increase stiffness of a tube is to increase its cross-sectional area. A fork with legs that have big cross-sectional areas? Nah, I'll pass.

Black Sheep has made some Ti forks. Google it.

Finally, working with Ti is different (read: more expensive) than working with Al or carbon.