De onde os estudantes de Hogwarts recebem dinheiro enquanto estão na escola?

Os alunos parecem manter seu próprio dinheiro entre seus pertences pessoais. As oportunidades para gastá-lo são relativamente raras até os anos posteriores.

He didn’t have any Muggle money, either. There was a little wizard gold in the moneybag at the bottom of his trunk, but the rest of the fortune his parents had left him was stored in a vault at Gringotts Wizarding Bank in London. He’d never be able to drag his trunk all the way to London. Unless …

_{^{Harry Potter and the Prisoner of Azkaban - The Knight Bus}}

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Harry gave Ron whispered orders and passed him some gold from under the Cloak. They left Zonko’s with their money bags considerably lighter than they had been on entering, but their pockets bulging with Dungbombs, Hiccough Sweets, Frog Spawn Soap and a Nose-Biting Teacup apiece.

_{^{Harry Potter and the Prisoner of Azkaban - Snape’s Grudge}}

O dinheiro pode ser enviado por coruja

A second, very small parcel contained a note.
We received your message and enclose your Christmas present. From Uncle Vernon and Aunt Petunia. Sellotaped to the note was a fifty-pence piece.

_{^{Harry Potter and the Philosopher's Stone - The Mirror of Erise}}

Aparentemente eles recebem dinheiro de bolso. Além disso, eles podem ganhar extra pegando o trabalho de outros estudantes.

GALLONS OF GALLEONS!

Pocket money failing to keep pace with your outgoings? Like to earn a little extra gold?

Contact Fred and George Weasley, Gryffindor common room, for simple, part-time, virtually painless jobs. (We regret that all work is undertaken at applicant’s own risk.)

^{_{Harry Potter and the Order of the Phoenix - Professor Umbridge}}

Seus pais pagam por coisas, como vemos os Weasleys pagando pelas coisas de Ron / Ginny. Hogwarts também tem um fundo para estudantes que não podem pagar por coisas, como Dumbledore diz a Tom Riddle:

When he had finished, he turned to Dumbledore and said baldly, "I haven't got any money."
"That is easily remedied," said Dumbledore, drawing a leather money-pouch from his pocket. "There is a fund at Hogwarts for those who require assistance to buy books and robes. You might have to buy some of your spellbooks and so on secondhand, but -"
_{Harry Potter and the Half-Blood Prince, chapter 13}

Além disso, (obrigado @Gallifeyan!) aparentemente o Ministério paga todas as mensalidades mágicas:

@emmalineonline1 There's no tuition fee! The Ministry of Magic covers the cost of all magical education!
_{JKR on twitter}