Snell Type D value

I would like to sell one snell type D speaker. I can not find much about this speaker online. I wired it to my system and it sounds great. I have a friend with a huge grin on his face about purchasing it from me. What is a fair price to charge him? Maybe a high end and a low end price? It works, sounds and looks great. Even the rear tweeter works. Please forgive me, I have zero knowledge of this speaker or company.