You can probably buy it but I strongly suggest you pay attention and buy a name brand vanilla from a well established store. This isn't a 100% way of knowing you're getting the best but it's better than purchasing it from a small store or a vendor.
The "real" vanilla extracts are more expensive and often the "great deal" extracts are poor quality and many contain coumarin "blood thinner and rat poison". It tastes just like vanilla.
I just say: Beware.