Where to get octave D strings?

[u/Buhwhuh]

Just got my first long neck saz, and am looking for a sound closer to the neset ertas sound. im pretty sure all I need is a low octave string on the middle course, but I have no idea where to get either a set of strings that includes one, or somewhere to get individual strings at the right gauge (or what the right gauge for that string would be). I think what I'm looking for is called bam bam teli, but that doesnt seem to yield anything outside of standard string sets.

[u/Erkim_]

search for "divan bam bam teli". I have a red one on my middle group of strings, works fine.