Prices just fluctuate. It's not all down for Genesis... Daze Before Christmas has shot up in price recently, and Pulseman is more expensive than I remember it being. Both of those are imports, but still.
Personally, while I have invested a lot in games, becoming cheaper is almost always a good thing IMO. No game should cost over $100. I don't like the fact that there are games out there that only rich people who drop hundreds of dollars can play.