The value of any collectible item, Pops included, is all dependent on availability in the market and demand by collectors. Short-term exclusives, such as those done for conventions, often never sell for “retail” price because they were only available at a certain location and time.   Depending on the popularity of the character, they might see a steady rise over time, or possibly level off once the demand for the character has diminished. Other items might be available at retail but sit on...