Got mine from deutschepartsusa on eBay. Appears to be a genuine german-made OEM part. I did the install, but didn't pop rivet the boxster stop so now I have to open the door up again. As it says on the other boards, if you don't put in the stop, the window rattles when you close the door. I vaguely remembered something about having to move a clip or something, but there were no instructions with the part and I thought maybe the rivet was associated with a mod required for some earlier doors. Based on this experience, I'd say they would be a good potential source for parts. Was upposed to arrive the 11th, came a week early.
Al