That's a little hard considering Star Wars is one of the most popular movies in history, from a marketing standpoint in particular. When it come's to movies like Blade and 300 then you've got a better chance of snagging a rare piece.
If you had something that was exclusive but you could sell it every year with slight changes for a million dollars profit you would do it in a heartbeat. Who wouldn't.
The thing about collectables I've found is that outside of very limited runs, something becoming valuable/collectable comes about in two scenario's.
1) Timing
2) Luck
For example I bought all the limited/1sts/rare Wolverine comics before the X-men films came out just because I like Wolverine. I didn't know down the track due to popularity that I'd be sitting on a gold mine.
As it is I kept em all, because I didn't buy them to sell them!