I second Lifter. He's a really great guy and does good work. Other people to look at are Gary Graley (if he's taking orders at the moment)- he and Lifter are both members here; and for high end kit: Kenny Rowe. Kenny's work is just fantastic. Leatherman here on the forums also does good, quality work.
Of those mentioned, I'm about to get a Graley sheath that looks pretty good, and I have a sheath by Lifter which is VERY well done. Hope this helps!