I'm not sure. If there are any, I would assume that it would be mainly for Macbook Pros or Airs or some other Apple product that everyone would buy. There would be too many specific types of keys that go on different laptops as they change the key layout pretty frequently, although that depends on the manufacturer and the model as well.
If anything, you may be able to get a cover for the whole thing that is customized so you can choose which keys say what. Other than that, maybe if you hit up SP they can work something out for you, but you'd have to get the exact specs on the keys and perhaps send them a 3D CAD mockup? It seems like a lot more work than expected, I know.
