Habanero (already mentioned) offers a very attractive price point for Ti bike. There are some fellow members who own one and could give more feedback.
Rodriguez Bikes have tons of experience building touring (custom and semi-custom) bikes and will build in Reynolds steel or titanium. They also have a higher-end "pure custom" division called
Trillium Cycles and will build you anything you want. They are great working with customers long-distance which is key to insuring a perfect fit.