Shopping works very simple. For 3G, you draw 3 cards. However, the drawn cards can't have a cost of 6G or higher. Be warned that the great amount of cards being drawn can easily cause you to overdraw. So just like Clover, don't use this unless you have 5 or less cards in your hand (this included).
This can be helpful alongside cards like Burgerpants, who will give you money as well as the space in your hand to safely draw the cards and give you more free choice of what you want to summon (though Burgerpants needs board slots, so it's still somewhat limited).
- Shopping Time (by Moonlightring)