Microscale might not be as out of the question as you might think, and their quality is excellent. I had them do SP&S decals for me (it's around 10 years ago now), and even with the 250 sheet minimum, I found enough people who wanted them that I could sell off some of the sheets to make back the money it cost me to have Microscale do the work.
You could expand what's on your sheet so includes what you need for the Shay, and ALSO includes other useful Western Maryland steam decals that nobody else makes right now. That would make it attractive to other modelers so you could sell them.
For example, I had them put HO versions of the decals on my sheet so both N and HO modelers could use them.
MS were really great people to work with. They improved and redrew the lettering and artwork I sent them, and were very good about exchanging emails with mock-ups of the sheets to make absolutely sure I got the sizing of everything exactly how I wanted it.
(and no... ha ha.. I'm not getting a kick-back from Microscale)
