Yes, I know that and there are a lot of those manual lenses around. I rarely see the RS lenses. The OP does not have a 15mm RS lens with a Nikonos II, it is a manual lens. And that would be the only one of likely interest to a few people.That's for the manual Nikonos lenses. Seacam and, more recently, Nauticam offer a service where they convert the autofocus Nikonos RS lenses to modern cameras, retaining the autofocus and electronic aperture functionality.
I think the adapter for the RS lens (13mm?) is something well above $7,000?
It is a shame that Nikon did not develop a digital Nikonos camera. But I suppose in the current climate they are doing good to even remain in business.
James