Some of these could probably work and be customized to your need. Tons of similar stuff like it on that site
http://graphicriver.net/item/4-poste...or=djedamrazuk
They are made with customization in mind.
or this one.
http://graphicriver.net/item/heavenl...emplate/244779
It's a flyer, but could work as a movie poster. A ton of options below it.
Your welcome..