Color a Dino and Kid Klown perhaps, but not Race America. Race America is simply uncommon. I would agree that Color a Dino / Kid Klown are potentially undervalued as they can both be a bitch to obtain, but demand just isn't there.
Hype definitely goes a long way in pricing, but that's the nature of the beast. Overhyped games can command more in value than sleepers which are rare but cheap. However, NES is pretty mature now and everyone has a good idea about what's what. Completionist collectors would have driven their prices up a bit if they realized "Hey, I haven't found this game for months and months, maybe I need to pay more to obtain it." That just simply hasn't happened.






