The rarest DVD that I own is the "Terminator 2 Ultimate Edition" (1-disc, complete with metal outer case). I was able to score it for $5.00 Canadian (and still sealed) at a Loblaws grocery store. It's got all the extras from the laserdisc box set on it. It's awesome. I also have the original 2-disc version of "A Beautiful Mind", and the 2-disc "Saving Private Ryan: 60th Anniversary Commemorative Edition", both of which went OOP quite a while ago.