If you have the complete kit with the car cover, seat covers, steering wheel cover, and red nylon carry bag, they bring around $500 on E-Bay.
I have the complete set but I'm thinking I'll keep the seat covers and the wheel cover for the 355. I guess just the car cover.
I bought a new OEM cover from these guys a couple of years ago, for £153 plus post and customs, it was still much cheaper than than dealer price with discount in the UK. prancinghorseclothing | eBay