I know I'm a minority here, probably even the only one, but I believe that posters are worth nothing. Don't take me wrong. I own about 10,000 movie posters and I will say that I have spent a large sum of money acquiring them over the years and still do. I am a collector, I have never sold a poster and don't intend to ever sell one. If my heirs can recoup what I have spent on my posters, more power to them, but I seriously doubt it. To me, my collection is worth about $10,000, because everything has a value and each poster I own is worth at least $1. Yes, even the Biebers.
What I'm trying to say is that I do not collect for investment. I collect because I like collecting, I spend some of my discretionary income on posters and it brings me happiness. I don't know exactly why, but it does. That's as much as I can ask from the hobby (and from life in general). Trends change constantly. What is cool today will be lame tomorrow, and vice-versa. There is no way to know what something will be worth 10 years from today. The 80s are hot right now, but a lot of people in their 20s have never seen Back to the Future or Ghostbusters. Nor do they care to see them. Old movies, whatever. So when their generation takes over, those posters will be relics of the past. Which is why I come from the standpoint that all of this is worth nothing, or close to nothing at $1.
No expectations.
In short, pricing trends change constantly and are completely unreliable. If you are collecting for investment, you are in the wrong hobby. Or you like risk.
T