Erm, unless there is a Yashica 80/2, I think you might have stumbled upon the Contax 645 AF 80mm f/2, which is a fully electronic lens. It can only be used on smaller cameras via a Contax 645-Contax N adapter converted by conorus, the last I knew. They can't be worth much, as they were the kit lens for this system. Around here, maybe 350-450 Euro or so? Nice lens, nice look, but not that sharp until stopped down a bit. A Contax 85/2.8 might be a better bet.