Any time you are looking into buying glass bottles in bulk, there are different places where you might find them. You could look at your local retail crafts store or kitchen supply store. Sometimes these places will carry glass bottles. Just make sure to take along a calculator, so you can figure out the price per bottle when they are selling them by the case. Take the cost of the case and divide it by the number of bottles to find out how much it is per bottle. For example, if the cost is $18 and there are 12 bottles in the case, the cost per bottle is $1.50 each. Also remember, some places may still charge you per bottle, even if you are purchasing them by the case.
Another place where you can buy glass bottles in bulk is online. Often the costs are less than your local retail stores, because online retailers do not have all of the added overhead costs of operating a physical location. Just remember to read the description of the bottles you want to buy, as this will tell you whether they are being sold by the case or individually.
In addition, under the current laws, depending from where the bottles are shipped you may not be charged any sales tax, when the location is out of state, which saves you a little bit of money to offset shipping costs. Some retailers might give you discounted or free shipping if you order a specific quantity of bottles. It never hurts to ask, especially if you are placing a large order.