Where to find it
As the title says, this is where to find instruments, music and accessories.
click on the links to go to a page.

http://www.helenjohnson.biz/

If you haven't found this website, this is tab editing software that is free to try and supports Mountain Dulcimers.
 

www.thedulcimerhymnal.com

If you are into Theory and study the dulcimer, this site is helpful:
http://www.jcrmusic.com/dulcitheory.html
http://www.jcrmusic.com/dulcitheory_sub/index.html

Also there are the Friends of mountain Dulcimers:
http://http://mountaindulcimer.ning.com/