RE: The ''How much is a card worth?'' topic.
^ Value is subject to change. I wouldn't price it above $100, either. Nevertheless, its predecessor "Pikachu Gold Rank 019/L-P", is in between $40 - $60 (folder). Its successor "Raichu Hyper Rank 044/L-P" (folder) is $300+. According to logic (and what I have seen on eBay and other Pokémon stores for the past year), Darkrai & Cresselia are in the middle at around $150.
@THE_LORD_Of_RANGERS - I have never seen the folder under $100 - unless an auction was neglected and the buyer became a very lucky individual. Or, if there was no folder (i.e. opened).