Perfect example of supply/demand. I think the only thing that will drive the prices down is when the people that were playing these machines as kids or young adults start croaking because the people that care about them will be gonzo. Since pinball was still very popular up until the early 90's I would assume there are alot of mid-20 year olds still playing pinball. That, imo, will be the last generation to keep this hobby alive. So I am thinking that this hobby will be around for at least another 30 years.
Think about the machines 30 years from now. They may still be around, but look at parts. That is what I think is going through the roof! I have a CFTBL and all I can think about when I play is "I hope the hologram doesn't go out" because there is no replacement for it.
Just my opinion, wth do I know!!