Hi folks,
I contacted Brake Tec (
http://www.braketec.de).
First they told me, that those cracks on my discs are really superficial only and are no safety concern on vented discs.
They said, that due to too small disc diameter and bad ventilation the discs overheat and create cracks.
Now they offered slotted discs (cast with better thermal stability) for 256EUR (pair price, part number is 2056641).
That's half the price of those BAER rotors.
There is no TÜV certificate or ABE, but a statement that they are of no safety concern (Unbedenklichkeitserklärung).
Plain discs come at 196EUR (pair, part number 56641).
A set of pads come for 83,50EUR.
Geiger Performance in Munich told me, that with 2001 GM has replaced the original Camaro brake discs with Heavy Duty discs. The pair price is around 334EUR, pads for 111EUR.
Cheers!
Gunnar