All good recommendations I'm sure. There are quite a few fine dulcimer makers around today. Unfortunately there are also a fair amount of shoddy ones available--and I think it's usually visible to the untrained eye. Look inside the box for glue spilled everywhere, watch for poor joinery, and small ones that aren't really a full scale dulcimer (should be at least 10 left courses, played on both sides of the bridge, and 11 on the right. Can have more, shouldn't be less.)

A hammered dulcimer is a relatively easy instrument to build, sort of, since they don't involve very thin wood or fancy bending. It's just a really strong box, so it's a matter of making it an elegant cabinet. Many succeed at this, some don't.

Bill