I have just recently gone public and my website is in the works.
Have you not seen any of my work ? I have pictures posted up here, anyway if not let me know and I will send a few pictures your way.
Is there money to be made ? Sure there is but as with any custom crafted item there is a balance to be struck and maintained, the success of ones venture sets at both ends of the scale and you can not forsake one for the other.
Quality and Quantity, you will have to craft your work to the highest standards possible to gain the attention of and orders from fellow enthusiasts, then maintain that standard.
You will have to be able to craft a certain number of that item to be able to provide for yourself and maintain a consistent inventory without sacrificing the above mentioned quality, so the answer is different from person to person.
My advice for what it is worth, craft your sheath's, show everyone that will take the time to look, seek and LISTEN to input with a thick skin because without it you will not succeed.
Find friends/relatives to use and test your work, if something is going to fail you want it to happen close to home not overseas in the thick of it.
Long winded I know, sorry !
There are a few other craftsmen here that I am sure can answer your question better than I, their work speaks volumes and the forums are lucky to have them.
K