This is a subject that has interested me since I also own a car with these "orphan" rotors. In regard to upgrading these brakes, I think you are missing the point. These are great brakes, torn from the 917 race car. I love that. Like the fredmiester I to am left a little breathless at the cost of these rotors. I have found replacement rotors at VCI but don't have any idea how good are: http://www.vehiclecraft.com/Brakes/vciweb4.htm
I too would love a good option.