Besides SASS, I shoot flintlocks, and belong to the Muzzleloader Forum.
This is offered on their site:
(2) FOR SALE - UBERTI 1847 Walker, ED Myers holster, belt | The Muzzleloading Forum
I don't know anybody, and have no dog in this hunt, so good luck with your search.
I've shown a couple of folks some of the ads on different forums, but never hear if anything works out.
If you make a deal, I would appreciate it if you could let me know that this worked out.
Make good smoke,