I believe the spoiler that you show is either AC Schnitzer or Alpina as it was specifically modified with the "gap" to allow a car jack to slide under the front for servicing in the pits for long haul races.
Contact Zaprace in the UK... I believe they make a version of this airdam
They are listed for sale on the Ahrend Tuning website: http://www.ahrend-02-tuning.de/index.php/weitere-angebote. No price is listed. I used google translate to send them an inquiry; hopefully they respond because I have zero German speaking ability.
I believe the spoiler that you show is either AC Schnitzer or Alpina as it was specifically modified with the "gap" to allow a car jack to slide under the front for servicing in the pits for long haul races.
If you need a contact - I live less than 15 miles from Ahrend... Just give me a hint.
Cheers
A