Where can I get raw flux?

Could you please tell me where I might be able to acquire raw flux? I've been searching for a reliable source, but have been unable to locate one thus far. Do you know of any specific stores or online suppliers that carry it? Additionally, would you be able to recommend any brands or types of raw flux that are considered to be of high quality? I'm interested in purchasing a quantity that will be sufficient for my project, so I'm also wondering about the availability and pricing of raw flux. Thank you for your assistance in this matter.