Here's a wild guess. I know that the Formula 1 - style shifter option on a Ferrari (the 360 Modena) was roughly about $5-6,000, at least the last time I checked a few years ago when they were still building that model. I can't believe Porsche would try to sell it for more than they charge for the Composite Brake option, about $8,200 here in the U.S.
Jim