$100 is nothing compared to $20,000. That's a car, or a college loan, or a business investment, or an apartment...not an old NES game that isn't even that fun. Those games cost upwards of $80-100 when they first came out.
True, but I wasn't comparing $100 to $20,000 directly. My point was that one's income can have a large impact on how we view an item's worth. $20,000 is quite a bit to me, but I understand that there are folks making more money than I ever will and can afford things I wouldn't dream of buying.
Plus, this game isn't ever gonna be played (I hope). If I'm not mistaken, its price has been going up (taking into consideration the VGA Grade) the past few years and is very much like any other investment. I imagine a few of the folks who've gotten their hands on one of these incredibly rare BNIB cartridges has made a good deal of profit from selling it.