Starbucks sells small bottles of vanilla syrup in major stores. To get a large bottle of Starbucks syrup like the baristas use, you may be able to buy one from the barista along with a pump, if they have enough stock on-hand. This is the best option since it only costs around $14, depending on location. You can also buy bottles of genuine Starbucks syrup online. Finally, Fontana brand makes Starbucks syrup, and is also available online.