What is the best way to dipose of my collection?
General mountain dulcimer or music discussions
If you are going to sell some of them, it's the shipping which will become the biggest chore, and the protective packaging so they don't get crushed in transit, and just getting suitable shipping boxes.
Are you saying you have over 80 dulcimers? You may want to get a well advertised estate sale going and a professional person to help with this. It's a whole lot of dulcimers.

says your nepenthes gaya.