Buy used, throw away everything except the so-called Original Trilogy discs, glue those three together (shiny side in), run a string through them, and suspend them inside a wall cavity, or even a hollow tree in the yard. You can pull them out if you ever need to prove ownership, but there will be no risk of an unsuspecting houseguest or innocent child accidentally being exposed to the films on them.
At least that’s what I did.