I had the problem too, a crack formed on the plastic window. I stopped by many places and they were charging from $1000-$2000
I went to porsche dealer and talked to the technican personally so no service manager crap trying to ripe you off. They direct my to a Upholstery person
"Bob's auto upholstery"
Redlands, CA 92374
Phone (909) 793-0043
He drove to my house took the top off professionally, and came back the next day with a brand new tinted rear plastic window and installed back on my car for $600
heres a picture of my rear window (sorry my car is really dirty wasn't washed for 8 weeks)
