Those grips won't need much to take care of what looks to be scratches in the finish.
Get yourself a bottle of Birchwood Casey Tru-Oil, and then mix a little with mineral spirits to thin it down to a 50/50 mix. Apply a light coat with your finger, it may take a few coats, to blend it in with the existing finish. You're probably aware of it but those grips would represent $250 of the price of the gun.
I bought mine in 2009 for $650, and I thought that was a lot... as previously said, they have no where to go but up. These particular guns represented a ground breaking change for S&W N-Frames at the time. It was the first factory produced round butt grip frame done on the N-Frame, prior to that a round butt N-Frame was only available from custom gunsmiths.