Hello,
It depends on what kind of winneries you are looking for.
The family owned estate/farmhouse winneries are usually not easily reachble on foot.
On the other hand, you could stay in a city like San Gimignano which is full of "enoteche", small bar like establishments that offer a huge variety of wines to try.
Im sure someone alse will provide some options for taking buses, as im not personally very informed in this regard.
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