With the original box and booklet?
Well, 150,000 copies were produced for the US market, probably 2/3rds of those sold through. One must imagine that a typical SNES box/manual retention rate was something like 15% (most people threw them away along the way), so a loose estimate would be something like 15,000 copies of EB initially survived the first little bit. Give attrition over the years to things like kid getting older and leaving for college, and mom throwing the stuff away or sending it off to storage never to be seen again, and maybe 7,500 or so are in the hands of collectors.
So it's decently rare, but there are less common games out there that don't demand the same kind of attention. There's a certain hype attached to it, sort of like Stadium Events. As a game, Stadium Events is mediocre at best, and can be had with a slightly different label for pennies. But it's pretty rare and is mentioned often as a hard-to-get NES piece, so the prices are astronomic for it. There are other NES games with the same rarity level that sell for a good deal less just due to less hype.