First of all, is this book valuable to you? For example, does it cover the fields you are interested in, or has a significant impact on your research or interest? If so, then this book may be worth buying, because you can learn valuable knowledge from it.
Secondly, consider the rarity of this book. If this book is extremely rare and may be a classic in a certain field, the price in 700 yuan may not be too high. However, if this book is not particularly rare and the price may not be high in the market, then the price in 700 yuan may seem too high.
In addition, we should also consider our own economic situation. If your budget is limited, 700 yuan may be a big expense. In this case, you may need to weigh whether the book is worth the price.
Finally, you need to be careful when buying out-of-print books. Some so-called "out-of-print books" may be difficult to buy in the market just because of copyright issues or the decision of publishers, but they may not be rare in fact. Before buying, it is best to investigate the background and history of this book to understand its real market value and collection value.
Generally speaking, deciding whether to buy 700 yuan's out-of-print books needs to be considered according to your specific situation. Before making a decision, it is recommended to carefully evaluate the value and rarity of books and your financial situation.