The Dark Dollar (D$) is the main form of currency in the Dark World. It is acquired primarily by defeating or pacifying enemies in battle or by selling items and equipment in shops. One-time caches of D$ can also be found in various places in the game.
D$ can be earned through various methods in the game:
- The party earns D$ when a battle is won. Leftover TP remaining at the conclusion of a battle is converted into extra D$. The party can earn extra D$ by fighting recurring enemies over and over.
- The Top Chef gives the party infinite Spin Cakes if they are used, sold, or dropped. The cakes can be sold repeatedly. However, each cake only sells for 3 D$, making this a very inefficient method.
- A chest in the Forest contains 40 D$.
- All items except for the Manual and Jevil items can be sold.
- All purchasable items, excluding Dark Candy, are sold back at half-price.
- If the party rings the bell in the room with the Starwalker Bird and then chases and touches the ambulatory portion of the bird that detaches and walks away from them, they receive 40 D$ from "Starwalker's radiant luster."
- When buying items in the Bake Sale, the sellers claim that their items cost 40G instead of 40D$. This is likely a bug or an oversight as GOLD (G) is the currency found in Undertale.