there are a few cars on this forum that are being parted out. one is a VR4, and it would have a sunroof. ask there.
if no luck, then check out
www.car-part.com adn find a car near you with a sunroof.
you might also try the parts for sale section at
www.3si.org (you can sign up only if you have an e-mail account other than the major free services like hotmail, yahoo, gmail, etc).