Unfortunately, if what you're interested in are newer posters (let's say, the past 20 years), you're a little bit out of luck. Most local poster artists have disappeared and, I would say 90% of the time, foreign posters look exactly like their US counterpart. This is one of the saddest evolution of the hobby, the lack of variety. If modern foreign posters look somewhat different, it can also be because the foreign arm of the studios used the US intl. version of a given poster (which you didn't see at your local theater, but which exists and is more valuable than any other foreign representation).
Erich, yes, Czech, of course!
Also, I forgot to mention, if the Yugo poster you're interested in looks different than the US poster of the same movie, then you potentially have something. Nothing against the former Yugoslavia, but their design tend to be identical to the US design. Now, if it's different and done locally, you've got a brand new ballgame.
Edited by T, 07 September 2008 - 6:10 PM.