1. Second-hand markets and online platforms: For example, second-hand shelves are often sold on platforms such as Xianyu, Taobao Second-hand and 58 City. You can search and contact the sellers on these platforms to find out the specific information and price of the shelves.

2. Source recycling centers or charities: Some resource recycling centers or charities will accept and sell donated second-hand furniture and shelves. You can contact your local recycling center or charity to see if there are any shelves that meet your purchase needs.

3. Second-hand furniture stores or shops: Some specialized second-hand furniture stores or shops may have the option to sell second-hand shelves. You can go to the local second-hand furniture store or shop for consultation.

4. Waste recycling bins: Some waste recycling bins may have second-hand shelves for sale. You can consult your local recycling station or waste recycling center.