To tell if a Pokmon card is worth money, you should check the set symbol, rarity icon, and condition
If you can look at one card, say, a Water-type card, and see that it's weak to Lightning-types, and you understand that the Lightning-type Pokemon that attacks your Water card will do twice as much damage
3 Plains By Ron Spears - $93.09 Asia Pacific Land Program #4 This card is from the Asia Pacific Land Program and depicts a field of beautiful sunflowers, all facing the same way and stretching as far as you can see
If heads, prevent all damage done to Squirtle during your opponent's next turn
#6 There's the fun of thinking about how neat Victimize could be
Note that the mana symbol is in the extort rules text, which means it doesn't count towards color identity, so you can play this in mono-black