I highly recommend these two shops for your citric acid/rennet/calcium chloride needs:
The SF Brewcraft guys were super nice. While I can’t afford a new hobby/addiction – I know that if I was to get into beer and winemaking next, this is a place I would frequent. Thia is a low key place where they were sitting down with customers to help them plan out their next custom beer recipe. There aren’t many places that I know of that would take this time and effort.