No, not really worth it.
Sealed NES games are really cool, and I get excited when I see them too. They're like... historical artifacts. They beg to be preserved somehow.
But, the bulk of NES games were "mainstream", and most mainstream people just don't think outdated games are worth anything. So nobody wants them. So the supply outweighs the demand.
If you search eBay for "nes sealed" you'll see a pile of old still-sealed NES games selling (or not selling) for about $10 each. Unless it's something people still want. Like, if you see a sealed copy of Dragon Warrior 4, don't be surprised to see a $400 price tag.