A while back we saw a sealed Stadium Events on ebay, which sold for over $20,000 dollars. However, it seems that someone still has a sealed copy of The Original Mario Bros. This is not to be confused with Super Mario Bros, which is an entirely different game. Similar to Stadium Events, it could be the only sealed copy that exists, though it’s hard to say if someone will buy it.
If you would like to buy the game, you can buy it now for $17,500 or simply make an offer. If this isn’t a game you like, according to the auction page it’s apparently part of a lot. It’s hard to say if anything of similar value will be listed, though you might want to look into it.