You can purchase nicotine sulfate from various sources, including online retailers, agricultural supply stores, and specialized chemical suppliers. It's important to ensure that you're buying from a reputable supplier that offers high-quality products and adheres to safety and regulatory standards. Additionally, be sure to check local regulations and requirements for purchasing and handling nicotine sulfate, as it is a regulated pesticide. Always follow label instructions carefully and take necessary precautions when handling and using nicotine sulfate.