Pah... what's "rare"? I suppose to e.g. a North American customer with a locked drive a non-R1 DVD that's unreleased in USA and, say, was only released in one country would be rare (Polanski's "Pirates", the US edit of "Fearless Vampire Hunters", the 2-disc version of "Dominion", for instance...). "Rare" as in the so-called "limited editions" (the 2-disc release of "Manhunter" or "Hellboy" with a film cell)? "Rare" workprints, officially unreleased films, practice shorts of future directors (Paul Thomas Anderson, Sam Raimi, Trey Parker, to name a few whose homemade shorts have been leaked) etc.? "Rare" due to their legal problems ("Ricky 6")? "Rare" as in "even the director won't acknowledge their existence" ("Manson Family Massacre"

)? "Rare" because only the person responsible for their existence was interested in somehow releasing them, and that in a tiny quantity (a certain awkward individual who plagues Sylvester Stallone with a certain plotless film of his comes to mind...