How to get things
Shells come from visiting (25 a day), unlocking achievements in any game (6 each) and finishing sets. You start with 150. Shells are never sold.
Coins come from achievements in released games or from the Coin Shop. A few classic pieces cost coins.
Logbook tiers, set rewards and seasonal events give the rest. Event pieces are free to claim while the event is on and come back every year. Every price is shown up front. Nothing is random. Shells are only earned by playing; coins are earned too, or can be bought in the Coin Shop.
