A lot of folks use Just Strings . A string is a string, after all, whether one calls it a dulcimer string or a guitar string. Just pay attention to whether you want loop end or ball end.
I actually have a deal with a local acoustic music shop. Whenever they place their order for single strings I add to the order. I get a good price and they get a small but reliable profit.
The hard part for me now is that in addition to a few regular-sized dulcimers, I have two octave dulcimers, a baritone dulcimette, and on its way is a full-sized baritone.Even if you don't include a couple of guitars, a mandolin, a couple of ukuleles, and more, I need a certified accountant to keep track of my string needs. It's enough to drive you loonie.
Dusty T., Northern California
As a musician, you have to keep one foot back in the past and one foot forward into the future.
-- Dizzy Gillespie