The best quality lock parts can be found at specialized lock and hardware stores or online retailers that specialize in selling lock parts. Some reputable online retailers that sell high-quality lock parts include Amazon, Home Depot, Lowe's, and Grainger. Additionally, you may also want to consider contacting the manufacturer of your lock to inquire about purchasing original replacement parts. It's important to ensure that the lock parts you purchase are compatible with your specific lock and are made of durable materials to ensure long-term security and reliability.