Pokemon Yellow/GB Zelda DX, A link to the past/GB Pokemon Silver/Gold/GB Sonic the hedgehog 2/Genesis Super Mario RPG/Snes Kirby Avalanche/Snes Tales of Destiny 2/Ps1 Vandal Hearts/Ps1 Rayman/Ps1 Pokemon puzzle league/N64 Phantasy star online episode 1&2/GC
Here are a few pretty hard to come by games I own. I know gamecube games are not that old, but phantasy star online episode 1&2 is hard to find even on the internet; you'll have troubles finding it below a 100 bucks. I know I have a lot more than that, I just don't feel like searching for them. (Old Snes and Genesis games are all safely stored in a box, somewhere...)
Oh, I almost forgot that old Nes of mine... You can count these games in too, that is some pretty rare stuff today.
Dragon warrior Kirby adventure Star tropics The legend of Zelda (Yes, the golden cartridge one) Super C (Contra's ancestor, you wouldn't believe such a game has one, but it actually does!)
I don't own any rare games - it's sort of a downer for me, since I used to own a GBA with a heapload of games (including pretty much every Zelda, colour or otherwise, to date) and a N64 - but all have been broken at one time or another.
Dammit, used to own Bad Fur day. Now THAT was a fun game.
I own an original version of Sonic CD for the sega genesis console that could take discs. I can't remember how the console was called, it really was just a Genesis that had both a cartridge and a cd slot. I'm too lazy to dig it up from its box hahaha...