Hi Robin,
I've been using the bowed dulcimer to play Baroque music for almost as long as I've been playing it. There is a huge amount of material available but i think a good place to start is a series of books of the music of Jan Jakob van Eyck. These are written for solo recorder or flute and are basically a collection of popular melodies of the time (1646) with variations. The melodies are fairly straightforward and simple and the variations become more and more challenging.
A good source for the books is The Early Music Shop in Boulder, Colorado. I'm sure there are others reading this that will have more suggestions.
For some of the very best performances of Baroque music I highly recommend the recordings of Frans Brueggen. He Is a fine conductor now, but in his younger years he was the premiere performer of Baroque recorder and flute. When it comes to style, tone, ornamentation and improvisation ( a big part of Baroque music) he is the best. He plays with such life and fire. The simplest pieces come to life in his capable hands.
Ken Bloom
http://www.boweddulcimer.com