The fiber optic sight: Standard Redhawks and Super Redhawks came with interchangeable front sights from the factory. You push a spring-loaded plunger and lift the sight out. Fiber optic inserts are available aftermarket but I don't know if any are available from Ruger.
Some very good gunsmiths do good work on shortening barrels and trimming excess weight from SRH frames. Putting the original front sight on the shortened barrel is a little trickier, so often is skipped in favor of a pinned sight. Which do you have, one pinned in place or one with a spring plunger allowing user replacement? If the latter, the gunsmith was probably good enough that his work would be worth having.
You might consider making a wager with the gun store. If they can get a letter from Ruger confirming this gun shipped from the factory in this configuration, you will pay their asking price. If not, $500. Just a thought.
I just came from a gun show this afternoon where I made some decent trades. Some 338 RCBS dies I would never use, for binoculars that I will. A full-flap Bianchi holster for $35. My bargaining juices are still flowing.