Hey John, I know zero about those. But honestly I’d start with a cardboard one from backyard instruments. It’s well under $100 and I can attest to that being a quality fretboard. That way you don’t have much of an investment. I’d say get the Folkcraft one if you are adventurous with building – but it’s a 27” vsl.
But – it’s awesome you are interested in dulcimer!
When playing those frets you need to be sure you are very close to the fret when pressing it down. Also if the action is too high at the bridge you may want to sand it lightly down on a piece of sandpaper (if it’s high feeling).