Twice, once for each claw.
The Both Necklaces are the wrong slot. This increases price by 30% or 1/3.Reasons to feel it should be counted twice: First off, even with the cost applied twice, this necklace is significantly cheaper than an Amulet of Mighty Fists (DMG, and the 'standard' item to improve natural attacks), especially at higher enhancements. Not to mention that you can put any weapon quality on it, where the Amulet is just a +X
So if Item cost 3K for +1 as example: the Guantlet price is only 2K for +1.
A cheaper item, would be Guantlet of Natural Weapons.
Again, it should be twice.Secondly, it will be enhancing both his claws, so later on when he adds flaming shocking what-have-you to it, it'll be there twice. A dual-wielding character needs to enchant both his weapons.
I feel RAW is the fairest.I am not really looking for other people's interpretations of the RAW here, I'm looking for your opinion as to which is fairest compared to regular characters.