What are the rarest DVD's out there?

I don't mean just big movies or anything but European movies, Asian etc?

There's a movie in find nearly impossible to get from Ireland called I went down.

There seems to be an extremely limited release and I've seen so few of them over the years. I think 2 all together since 1997.

Even the Irish Film Institute has no copies of it and they basically have all Irish movies and a fair few rare ones.

And it's a Brendan Gleason movie so not exactly a nobody or anything like that.