http://www.flags.com/p120074/Porsche/product_info.html
I ordered some a few years ago from this company (good gift idea). One had the crest turned lengthwise and the others like the picture.
edit: I just googled and found:
http://www.weldtechnology.com/disp/Porsche-Banner-Flag-911-356-944-928-mc32021-6753.htm
When I copied the link, it had a lot of different Porsche banners, but now just two showing after I click on it.
Last I looked, Pelican doesn't sell these.