Quoted from sbmania:Two factors at play. As the cost of new digitals continues higher and higher, EM's remain a more affordable but still fun choice for collectors. But as the population of pinball players that played EM's in the wild ages, demand goes down. Someone smarter than me can graph those two trends out to see where they intersect, and perhaps predict where prices are going!!
Region I think is a big factor. But generally agree with the statement above. I hear how interest in EMs has declined but I can't buy them like I used to. What used to be a $50-$300 project in my area has generally turned into a $400-$600 project.
When I started you could buy 70s multi-players cheap as interest was low. At the time Clay was promoting single players as the best choice for deeper rule sets. Now it seems a collector that has a modern collection may pick up an EM as a cheap alternative but would prefer a later model multi-player. I'd bet most of the heavy hitter Wedge head and woodrail collectors are full up now. Interest seems to have declined but asking prices haven't. Many more of those games available just not affordably.
As mentioned I think Bally has become the new hot EM manufacturer to pursue. I remember when Bally Brian Saunders was the odd man out. He apparently had it figured out all along.