Wei Ying, 31, is picky in buying new stuff, but she always buys new clothes with profits from selling old ones and she had a collection of second-hand books and DVDs that was the envy of college classmates.
In May, she founded the Deja Vu online store, specializing in used books.
In a two-storey apartment in north Beijing, piles of books squeeze the already cramped space where some staff clean dust books with cloths, erasers and alcohol, while others search out orders from bookshelves.
New arrivals often sell within a couple of hours.
"My recycling dream is realized," says Wei, adding Deja Vu is in demand as more Chinese buy books, but have limited space to store them.
Since opening, it has attracted more than 50,000 registered users, including 10,000 active trading members. It serves 10 major cities and will expand nationwide by the end of November.
Bricks-and-mortar bookstores have been on the rebound since 2014, but a report by Beijing-based Openbook.com says for the first half of 2017, Chinese online bookstores saw sales up 30 percent, while offline stores were in the red.
On the Douban ratings and review website, a book addict club has almost 350,000 members, who show what books they read and recommend and discuss how to swap or trade used "treasures".
Posts like "200 yuan for 10 used books, Beijing only" and "Used books, good bargain, freight" pepper discussions.
"We bookworms are reluctant to throw out books. Due to limited room, I have to give some away, but I would like to find other book lovers to trade with," says Wang Hongfei, a researcher at Beijing Normal University.
Like many book owners, Wang once carried around a suitcase of books, looking for buyers with similar tastes.
However, Deja Vu has reduced buying and selling to just a few taps on a smart phone. Vendors need only scan the barcode of books and get the resale price, then wait for the courier to collect them.
Unlike other major book trade platforms, Deja Vu offers standard verification, pricing and packaging.
When someone places an order, the vendor is notified and can collect the money online.
Wei was inspired by the BOOKOFF, Japan's largest offline second-hand bookstore chain.
Books are bought for 10 percent to 30 percent of the fixed price, and the store can sell 1,000 books a day and take in another 1,000 books.
"More users are telling us they hope to find rare books on our platform, so we've extended the range," says Wei.
However, it won't deal in specific test books, fake science, personal life guides, tainted books or counterfeit books.
Wei says books are often verified online by machine, but some counterfeit books are very like the real ones. If counterfeits are detected through format or print analysis, they are sent to recycling centers.
Chinese started trading books online a couple of years ago, but Wei says owners couldn't communicate directly with each other. She wants to provide community-like services.
"We should build a music festival rather than a railway station. In a railway station, nobody wants to talk with strangers, but people talk more easily when they share similar music tastes," she says.
Users used to thumb through old and dirty books at used goods markets, says Li Chan, operation chief at Deja Vu. "Now they sell and buy at ease. Often they will attach a message for buyers, hoping to share their experience."
Wei cites the Dr Seuss classic, The Lorax, which chronicles the plight of the environment as an example of sharing knowledge and saving resources. Her copy from childhood has been passed down to other children. "This way, recycling creates value," she says. "Books show one's life stages and one's mind."
Wei wants to add more goods to the platform, like used electronics and furniture: "It's worthwhile when more quality second-hand goods are used by more people."