Yup, even the cheesy and poorly made items that are sealed and rare are worth a lot of money now. As time goes on, nearly everything NES becomes rare. We've all had them and sold them for $15.00. If we only knew then what we know now.
That's why I always keep any sealed game or accessory that I can get my hands on. I know it's probably going to go up in value sometime in the future. If you are young enough, buy any sealed game bargain you see. Not to play with or open, but as an investment. You cannot lose money and that's better than stocks.