How do you find out how much cards are worth?

Ill make a list for a high rare :)

Honestly it varys and is ever changing depends on the event at the time so the amount something is worth changes during holy wars you'll notice that HP is worth allot more then cw water but depending on the event that could change but just trade rares for rares and so on and you'll be fine just be careful don't trade for anything that doesn't have 4 circles in the bottom right corner those are treasure rares and will be obtained threw playing the game all on its own

Yeah, every card is different. Certain cards are worth more because of their abilities or Attack/Defense when maxed. Also, things change as the market changes. As far as rares go, most people will trade 1 for 1, however high rares and up are different. For example, Vampire Lord (Big hit to foe's man ATK) will sell for about 20 Holy Powder. Archdaemon (Bit hit to foe's DEF all) is selling for around 35. But, you never know, sometimes you can find people who will trade 1:1 for HRs as well.

Check the Message Board for similar trade offers and compare prices.

I have some rares and high rares to give away. To anyone looking to make a trade fot pop singers. Send me a trade request or message::Four20Crusader