Probably not a bad deal if that's something you're looking for. Grips are terrible for a Colt, but thats easily fixed. I don't know what the value of the ammo is though. Don't keep up with prices now that I reload.
About 150 for the ammo & extra mag, but unless you like those grips figure a minimum of a minus $50 for replacements, bringing cost of pistol to $700. I got mine new for $850 OTD so $650 to $700 not bad, but not a steal. Like vincent says, best to be able to check it out FTF & he might even come down a bit when you're standing there with cash money in your hand. Maybe he still has the original grips & will throw them in. They'd be better than the ones on it, IMO.
If you're careful & it's not too deep, that idiot scratch can be polished out & no one would ever know it was there. Rest of it comes down to if you really lik the pistol & I can vouch for the XSE being nice although mine is the Commander size.