We have the option of selling cards for a very small amount of coins, but since there is already a gp value associated with these, can't the selling price be more inline with the coin value of that gp (maybe half)?
Example: I have a random 6* card that costs 15k GP in the shop. The value of that GP is a donation of 1.5 million gold. Couldn't my selling price be 750k gold?
I've collected a great deal of useless 6* cards from the shop and gems for the sake of completing the monster book, but once I have it registered, I'd like to clear the room... unfortunately, selling a 6* card for 225 gold seems completely pointless, so I've never done it.