Where can I find (buy) Kombucha mushroom, or SCOBY?

Where can I find (buy) Kombucha mushroom, or SCOBY?

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I already try walmart but I only say the small mushrooms that we use for other foods, is there any other known groceries stores I find Kombucha mushroom, or SCOBY at?
Also does it have to be done with sugar?
I don't want to use sugar, And can I use sugar cane tea, instead of tea bags?
sugar cane tea is healthier.
I'm open for other suggestions, thanks.
There are some answers for your reference as below,you can choose your best answers

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You might try using kombucha extract which you can buy on the web, from a lot of places, as this link shows::
http://www.google.com/products?q=Kombuch...

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