A. The Death Tarot/Doom Darts sells for 1 gil. If you were referring to the Viper Darts/Trump, they sell for 6500 gil. The question could be a bit misleading because the Doom Darts and Trump were actually switched during translation in the SNES version. That's why you throw cards when you attack the Doom Darts and throw darts when you attack with the Trump.

Q. What key item do you receive for completing the Soul Shrine?