Here is a physical brick and mortar Chinese bookstore and another online one:
Sino-American Books & Arts Co. (中美書店) – This is a physical bookstore in San Francisco and doesn’t have a website. SM, a fellow parent in a FB group, mentioned that she get books and CDs for her daughter here and that they have reasonable prices.
Site Language: No site available. Not to be confused with the Sino American Books, which is a publisher of English language books devoted to Chinese stories and topics.
Physical Locations: 751 Jackson Street, San Francisco, CA 94133
Contact Information: T: 414-421-3345; F: 415-651-8515; email: firstname.lastname@example.org
Products: Readers, pre-school word books, storybooks, novels for middle school and high school kids, DVDs, CDs
Product Languages: Traditional, Simplified, zhuyin, pinyin
Senseio Bookstore – Recommended by another fellow parent, SKC, this one is online and also does tables at their school in Los Angeles during book fairs. There are a lot of products and if you are in LA, you can even go by the owner’s house and browse also.
Site Language: English
Physical Locations: Yes, but by appointment only. Los Angeles, CA
Products: Chinese or Chinese/English bilingual books, magazines, Cultural Arts & Crafts, Gift Items, reference materials, and other multimedia, DVDs, CDs, Books for all ages (including adults)
Product Languages: Traditional, Simplified, zhuyin, pinyin, bilingual