Remember inflation. I guess there's a roughly 3% inflation in the U.S yearly.
This means that what was 60 dollars in 2001, is in 2006 almost 70 dollars, meaning that in reality they cost the same, just that the value of the coin has decreased.
http://www.vgchartz.com/games/userreviewdisp.php?id=261
That is VGChartz LONGEST review. And it's NOT Cute Kitten DS