You can obtain the Volkner (2-Diamonds rarity) card by opening Space-Time Smackdown: Dialga from Space-Time Smackdown set
You can pay real money to buy jewels, which you can use to add 5 moves to a level youve just failed, giving you a better chance to beat it, or you can spend them on coins or on extra lives
The Pikachu VMAX rainbow rare, in particular, is very desirable and commands hundreds of dollars on the secondary market
Typical RRP for a Japanese booster box is 5500 ($36), of the four most recent sets, Black Bolt was around 12,000 ($79), White Flare, 11,000 ($72), Mega Symphonia, 9,000 ($59), and Mega Brave, 12,000 ($79)
Mew [1st Edition] #51 (Pokemon Japanese 20th Anniversary | Pokemon Cards) prices are based on the historic sales
Just be sure to order as early as you can to make sure everything arrives on time