In the past, this would’ve been impossible! And, in fact, many people do still buy entire sets for the extra figures! Now, you can easily go to the Lego store and find what you’re looking for! Pretty much anywhere on the web you will be able to get some extra figures! Or, simply contact the seller through your order or contact Lego directly concerning the product in question to ask about an extra figure and inquire if there’s a serial number that can be used in reference for it in the future!