Many cards break into the 3-figures if they're not printed enough, like Power Artifact, and its not uncommon to get into 4, 5, and even 6-figure price ranges for the ultra-rare
There are six primary ranks for each format: Bronze, Silver, Gold, Platinum, Diamond, and Mythic
Thats about all the subtlety you can find here
Over at TCGplayer, they took data from over 8,000 packs of Astral Radiance in order to determine just how difficult it is to pull some of the recent sets hottest cards
So the value of a card is connected to the value collectors will put on it, and often an investment into a Pokmon card could take a while to pay off
Links and References This is the first time I feel the need to include links to rulings, only because the rules are such an important part of this CotD