MP. You can View All Items on sale here and recent Price Changes. The Trading Cards Shopkeeper completes a stocktake every 5 minutes so new items may be on sale here in 3 minutes. You can invest in the Trading Cards Shop for
1,019MP per share 
47.5% 
Battle Arena
Boosters
Bubble Pit
Elite Gym
Gym
High Scores
Knutt Knight
Sumo Sally
Talon
Trading Card Collection
Transumption Temple
Zetzilla