There are many on Taobao, most of which are pirated, so it is difficult to buy genuine ones.
I think this kind of exam book is lost after reading it. There is no need to buy a genuine one, which is a waste of money.
There are two common types on Taobao. One is that you can buy a set of four books for twenty or thirty yuan. That quality is really poor. Some of my classmates bought them, and some of them scattered a page as soon as they used them. Some of them were badly stained and the covers faded. I don't even trust buying this kind of book.
Another is that you can buy a set of four copies for seventy or eighty yuan, usually under the slogan of genuine, which is actually high-quality piracy, which is not much different from genuine, comfortable and affordable. I bought this set from 78 yuan. The effect is very good, I am very satisfied.