The trademark to the vintage PEZ dispensers is in the low model numbers inscribed on the bottom and the original designs that did not include feet. It is the combination of these two facts that is a key when dealing with a PEZ dispenser collection. Some not so trustworthy individuals have removed the feet from the dispensers and tried to pass them off for the original design. That is why the model number goes hand in hand with the feet. Making sure that if you do invest in a PEZ dispenser with feet that the models numbers are low and consistent with the original designs that will help protect your investment from fraud.
Other types of valuable PEZ dispensers are models that were made in a very rare form. An example being the Elvis dispenser created for a film. These and special holiday collections are in rare form and hold a great value to those who can get their hands on them. PEZ designs these and only produces so many to keep with the collectors and the demand for more.