Did some googling, came up with a generally accepted list of distinct titles as 677 licensed games. NintendoAge counts it, it's derived from a list that used to be on Nintendo's own site with some very minor changes, etc etc. Close as you come to an "official" list of licensed titles. This does include Stadium Events (so I will likely never have the full 677 but we'll see), as well as counting Punch-Out!! as different from Mike Tyson's Punch-Out!!, because both games do have semi-significant programming changes. It's not including minor revisions or label variants. I personally will hang on to a label variant if I find it, but won't go out of my way to collect them (nor screw variants). I think I have the major label variants already - Metroid yellow label and Zelda 1/2 gray carts, though I don't have Blades of Steel red label (I don't have either Blades of Steel actually).
I do intend on also getting the Tengen carts and the other "major" unlicensed games, but they're significantly lower on the list, especially Action 52, Maxi 15, Caltron 6, and the Panesian games. If I'm going to be dropping that much money, I'd rather drop it on Little Samson or Dino Peak, those are at least kinda fun games and not 100% showpieces. I actually have a good chunk of the Tengen carts already, notably someone from here got me Tengen Tetris a while back which I'm pretty sure is the most expensive of the lot. I also have 2 of the 3 AGC games (Chiller and Death Race) so I really feel compelled to pick up the third, because those games are hilarious. Pirate games (which includes Sachen in my eyes), games that came out significantly after the NES's lifetime, that's a no-thanks for me unless they just kinda show up in lots.
As to "help out"... well... http://rfgeneration.com/cgi-bin/collection.pl?name=KalessinDB&folder=Collection&type= is my current collection (sans about 10 games I have en route from last week's purchases, I tend to mark them in once I have them in hand and cleaned up), anything you guys are willing to let go, especially the common carts, I'm happy to acquire. If y'all flood me, I may have to pace myself, but I'm very interested. When I get down to sub-100 games I might start sending people on flea market/game store hunts since even game stores tend to be a touch cheaper than ebay, but that's a ways off.
And yes, I'm well aware of the cost of Snow Bros, Bubble Bobble Part 2, Surprise at Dino Peak, Little Samson... like I say, the number of games that hit that level are way lower than SNES, I think it's doable.
Other than Stadium Events. F that noise