Originally Posted by smd4

"NOS" means "New Old Stock." A new item, usually in the box, never used, that's been sitting on a shelf somewhere or in someone's closet.

FWIW, I paid $100 for my 12-23 and $157 for my 12-25.

You can filter eBay to show only "sold items," which should give you an idea of what other similar items are selling for.