The 35/2 Nikkor-O is much sought after by the m4/3rds crowd. I was kinda surprised to get my current copy for $65 or so. Granted, it was non-AI, but I did have a beater that had the AI ring on it. Six screws on each lens, and the rings were swapped. KEH usually has them for about $100-$130, depending on condition. Note: the O was never an AI lens, so, it'll be either a milled AI'd lens, or a factory AI'd lens, even if KEH or eBay sellers call it an AI lens. The AI/AIS lenses usually run another $60-$70 over the O lens, btw.