Plain (no ns) are regularly seen in my area for $510 new. If you want to move it quick, price $75 or so under new in your area (if you are going to try to sell locally). If you don't mind waiting a while, price it $50 under new. NS would probably add about $50 to the asking price if they're recent manufacture. BUT, if they're any more than a 6 years old, I wouldn't pay any more for them than I would for standard sights (this is due to the 12, sometimes 15, year service life of these sights - they start to dim well in advance of the end of their service life).