The only sealed NES game I ever owned was a copy of Kirby's Adventure.
I had the same dream, 'cept I wanted them all in
at least the original boxes. If it had the box, then I could forgo the fact that it didn't have the instruction manual, but I wanted at least the box. When I sold off most of my collection to pay for stuff when I found out I was having a kid, I got rid of just over 200 games. At the peak of my collection, I had 249 games in the original boxes, about 80% of them with the original manuals. That's just shy of 33% of all US released titles, according to the GameFAQs database of US releases. There are 799 official NTSC/PAL releases, and I believe 816 if you include unlicensed games.
I'll see if I can find that picture...
If I ever win the lottery, or find a good paying job (or, really, just get full time at my current job) I'm going to start collecting again. I know I won't be able to finish the collection (games like Stadium Events are just too damn expensive), but I'm hoping to make a decent stab at it again in the near future.