I have a Mamiya-Sekor 250mm/f6.3 lens for sale, in 90%+ condition. The Viewing Lens shows some mild fogging (it's a bit exaggerated in the 2nd photo, due to the flash) but that can likely be cleaned (use a spanner to remove the front element retaining ring, then clean as needed); the Taking Lens is clear - no fogging, fungus or scratches.
The shutter fires cleanly (B-500), and sounds accurate (I still need to build that shutter test device!). The aperture is continuous from 6.3 to 64; there are no fixed stops. The shutter leaves are in excellent condition; no signs of wear. I suspect this lens has seen little use. There is a flash attachment, and can be set to X or M as needed.
Asking $150, shipping included. It comes with a cover for the rear elements, but no case. I saw two on that other auction site and they're asking in the $200 range when S/H is added.
This would be a great lens for sporting events, when you need to get close to the action without putting yourself or your gear at risk! The combination of the high shutter speed and high depth of field would give you great shots such as horses coming down the stretch, race cars navigating sharp turns, a kayaker running the rapids - use your imagination!