Instructions
Look for bottle stoppers that have a name stamped on the top. Bottle stoppers occasionally have the name on the sides, but these examples aren't worth as much because the information can rub off over time. You'll also find bottle stoppers that are more generic and without any identifying information, which aren't worth as much.
Decide what you want to collect in terms of bottle stoppers. Some collectors look for bottle stoppers from a particular location. They typically collect bottle stoppers from a local bottling plant or from the area where they live.
Choose between collecting bottle stoppers, or bottles with bottle stoppers on top. Bottles that are in good condition, with the bottle stopper still on are typically worth more than single bottle stoppers. However the price varies depending on the rarity of the stopper and the bottle.
Pick a specific bottler or style to focus your collection on. You may focus on finding bottle stoppers from alcoholic beverages, or limit your collection to soda bottle tops. Another idea is to use a specific bottler such as Anheuser-Busch or a certain brewery.
Buy bottler stoppers that collectors refer to as strong. This means that the printing on the bottle stopper is clear and free of any blemishes or damage. You should also be able to see all the images on the bottle stopper and the colors should still look bright, which increases the value of the bottle stopper.