You may want to post a question on their FB page
https://www.facebook.com/windrestrictor#!/windrestrictor?sk=wall
and ask if they would provide a discount to the members of the 986forum as they have in the past, at least worth a try. Also if you did not want etching the plain tinted windscreen is $119.00.
I think I paid about $75.00 with "Porsche" etched in on the bottom of the screen at the time due to discount provided to forum, others got theirs free of charge for the use of car for advertisment (look at the Guiness beer one) he was/is a forum member.