At least JJP and Stern actually make and deliver pinball machines! They may start commanding a premium for performance. Even though they are charging a lot, it's better to pay for something that you know you are going to get rather than getting duped...then you are definitely overpaying.
At the end of the day it will be supply and demand that will dictate if this type of pricing will hold. It's great to have increased value for your machine, but it still needs to be affordable for all pinball hobbyists or else it becomes an elitest club and what's the fun of that?!