Inkjet transparency sheets like you'd find at your local office supply store [0] are polarized; you may not have to order polarizing film.

I used to own a car that had an LCD display where the orientation of the polarization was perfectly set so if I was wearing my polarized sunglasses, the screen was blank. I cut out a little overlay made out of an overhead transparency and fixed the problem.

0: http://www.officemax.com/office-supplies/presentation-equipm...