Pocket Monsters (Pokemon) Red, Green, Blue, Yellow, Gold, and Silver on eBay. Those are Japanese versions BTW.
Decided to lock Gold and Silver in a treasure chest so no one would ever see it (by the looks of it, Pokemon Gold and Silver is unplayable since whenever you save the game and turn it off, the save file is deleted due to battery issues. And I would have to say (the Original) Gold and Silver are my least favorite of the series.