1. Regular supermarket: Go to a reputable regular supermarket, such as a large chain supermarket or a supermarket specializing in food. Supermarkets will have certain quality control and supply chain management, and can provide high-quality food, including authentic Lycium barbarum.

2. Pharmacy: Some pharmacies also sell health care products and Chinese herbal medicines, including Lycium barbarum. Choose a regular pharmacy, and you can buy Lycium barbarum products with guaranteed quality.

3. Online shop: Buying Lycium barbarum online is also an option. Pay attention to the choice of reputable online stores, especially those with relevant certification or evaluation. Reading other consumers' comments and feedback can help you judge the reputation and product quality of the business.