No such thing. An individual game can certainly be price under or over market value... But as a whole, there is no such thing as "the entire market" being over/under priced. The entire market is as it stands and does not need to prove itself against any other entity. Does not matter what the product is that's being sold.
Now, "undervalued" or "overvalued" by the average pinball enthusiast, then you could be on to something.