I'm the same way as you. Just wanted posters for my cinema/bedroom. So I picked up two 27x40 of my fav movies, Up in the Air and Wall*e on eBay for $10 each. Look there first. Make sure they are double sided and not wrinkled. If you buy from the right company, they send them in a tube, packed perfectly. You won't be disappointed.
I went up the walmart's craft/photo section, and they had a 27x40 collage frames, with plexi glass for $20. Not bad! I threw away the collage mat, and the poster looks superb. 27x40 is the ideal size. It seems big, but it's lifelike. It's what you see when you go to your cinema. So that's what I recommend.
Here there are.
I know I'm 4 years later with this, but... Why do you recommend 2 sided over 1 sided? What is the difference? I seriously do not know. Thanks