How much is this Harry Potter poster worth?

I have a poster from the prisoner of azkaban which was originally used in an odeon cinema when the film was released. Ive had it on my wall ever since. Its a picture of sirius black holding a his prisoner id and its a hologram so at certain angles he disappears. Ive just seen something very similar on ebay go for about �170 but cant find much else on the internet apart from the fact it might be quite rare.