Elves do not rely on money in the same way humans do. While money is exchanged for goods and services, it is not a driving force in their society and is not a factor when considering social classes or nobility. Elves are given a birth fund with more than enough money to support them comfortably through life. They do not have to work like humans do; they choose to work because it is an interesting thing to do with their very long lives because, otherwise, they would basically do nothing their entire life. Each birth fund is 5 million lusters, with 1 luster equal to about 1 million human dollars, making each birth fund worth about $5,000,000,000,000 in human money. Although most elves get their fund at birth, Sophie received hers when she first arrived at the Lost Cities in Book 1: Keeper of the Lost Cities because she was born in the Forbidden Cities to a human family. Lusters are stored in a green cube carried by each elf. To pay lusters to another person, you swipe the green cube.