I had a local locksmith cut a courtesy key that only opens the door for 100 bucks. No guarantees that it would work. It didnt even go into the door lock until I compared it to the other 2 keys that I have and noticed the end of the key is blunt not pointed, so I filed it square and it worked. I got lucky, my key was inadvertantly locked inside the car. Call around to youe local Mercedes dealer or Porsche, and ask who they use as a locksmith. He will have the ability to laser cut your key providing he has the proper blank.
....Addional- 3D Elite pro was the "LASER ASSISTED" key cutter used, a type of a laser guided 3D router. State of the art in key cutting.