People are realizing they just don't make machines anymore so basically a supply/demand thing as far as prices. (Stern & JJP making 5,000 to 10,000 machines a year is a drop in the bucket compared to 100,000 to 250,000 machines a year being made in the 1950's through the 1990's).

As far as why demand is up to begin with I think the online stuff has had a big influence on that.

Bottom line is less machines coming from operators, more collectors, more interest in the hobby, etc all add up to higher prices on machines.