Your family only allows you to buy ordinary books. The budget there is about 4500-5000, so you still need about 4000 yuan. My suggestion is to go to a bank, transportation or Agricultural Bank of China to open an account. Open a financial management project called Fund Fixed Investment. If you invest 300 yuan every month, the bank will automatically deduct it. 3,600 yuan a year is almost enough. It depends on the living standards in your area and whether 500 yuan is enough for you. It’s been a month. If you still can’t use it all, you can save more. Moreover, this fund will grow. That is, if you save 3,600, it may become 4,00 in a year. Hope it will be adopted.