If you want kydex you should send it to someone - there is enough variation among the game wardens that kydex molded for a different knife may not fit.
If leather is preferable, then the Busse Company store has some tan sheaths available. They may have been designed for the standard game warden, but you can probably wet-mold them to the fatty. Folks at the store should be able to tell you if you email them.
Beyond that, there are a bunch of sheathmakers on the Busse forum - you might even find one who has this exact knife. I think all of the guys who make sheaths for pay do a good job, so it's more a matter of what design you want.