Roush 13-inch Rear Rotor Replacements?

Does anyone know where I can find a set of replacement rear rotors for the Alcon 13-inch rear brake kit for the 99-04 Roush Mustangs?

I'd really not to pay the exorbitant prices on the Roush website. ( ROUSH Performance: ROUSH Ford Mustang RH Rear Brake Rotor ) $415 EACH !?

I was hoping perhaps Baer, Brembo, or Powerslot made a replacement, but I can't find anything. Is there anything out there?

Thanks for your time!