I have an arrangement with my contact in Beijing that I will send him any books that I find in my travels in China. The last time I went to China, I sent him four boxes of books.
Not every book is available in every bookstore, so I bought what I could in one province and mailed the boxes, and then bought what I could in another province and mailed them.
I have also worked out an
arrangement with a businessman in the US who takes the books I order for him in the US and puts them in his suitcase and carries them to China and mails them to my contact in Beijing.
What I like about my contact in Beijing is that he doesn't hoard these. He gets them out to his co-workers and local Chinese to be able to use.