Cannabis Accessory SEO

Hello, I am considering the take over of a cannabis accessory company. They have an existing site with good authority, but they were wrecked by the HCU update in March. They had made up some ground before hanging up the towel. How competitive is the cannabis SEO market. What style of budget am I going to need to start digging a site out of the whole in this niche? Is this something a guy with basic SEO understanding can handle, or will I need to bring in a professional?