I have a rare game -- what do I do next?

Howdy people,

Long-time Nintendo fan here -- first time user of the forums. I know it's impolite to post immediately but you'll see why I am doing so in a sec--

I recently dug out my old video game stuff and found some unopened games for Gamecube. Among them is a NCAA College Basketball 2K3, still in its original packaging.

Elsewhere on the Internet in appears these... simply do not exist. There is one on eBay presently.

What would you all recommend I do next? Please note this is NOT an offer for sale.