I think a good idea would be first to go to a framing store, check for the different products they offer and the different price ranges.

This is a pretty good link that offers some inexpensive options: http://www.learnaboutmovieposters.com/ne...

Hope it helps

Cheers

Im framing a 20x30 poster and I need a plastic front cover to protect the poster from the elements while framed on the wall. I've looked on amazon and for a 20x30 its like $15 bucks. Thats ridiculous for a thin piece of plastic. Is there any place I can get a low quality piece of plastic to just protect it.