I've been addicted to kombucha from first sip. It wasn't really the probiotics or other health promises that did it for me — although I'll take those, too! It was the way it tasted: like tart green apple mixed with sour stone fruits, but with an underlying sweetness that keeps it all together. And fizzy! I couldn't believe that something this delicious could actually be made from tea, of all things. Or that I could make it at home with a few very basic ingredients.
Excellent guide from thekitchn.com: How To Make Kombucha Tea at Home
Leaving this here for reference because I've had this tab open for weeks and haven't yet found time to make a batch. I made sauerkraut a couple times now, and I was shocked at how easy, cheap, and delicious it turned out. Kombucha is my next project.
Also -- etsy is a great place to find Scobys to start with if you can't find one locally. And cheap too! For instance: https://www.etsy.com/listing/265427402/kombucha-scoby-with-starter-tea
View the whole market here: https://www.etsy.com/market/kombucha