Thanks to an astute visitor (hi Troy), we discovered that the console pages,
such as the one for NES, were displaying a blank space in the "90-day Price" column if we had no price points for a game during the previous 90 days. It was quite unclear what the blank space meant. For such low volume games, the 90-day Price column now shows "none" and hovering your mouse over that link explains that there are no price points
for the game during the last 90 days, but you can still click the link to see the historic prices.
We have some changes in the works which should prevent this kind of thing from happening, even for low volume games, but those changes aren't quite ready. Thanks for the feedback and keep it coming.