I look at this and see two questions. One a playing question and another a building question. Personal opinion is to start very basic to learn the instrument, the fretboard, the different tunings and so forth. I would use a realatively inexpensive student dulcimer for this. Once I got a feel for the instrument and made some discoveries into what you can and can't do with the basic dulcimer and the type of music you desire to play, then I think it would be easier to answer your second question as to what type to build.
I hope you get where I am heading. Pain Meds kinda cloud what I am trying to say but I hope it comes through. If not ask more questions.
CD