It's a thing for sure. For me, as far as new items go, it begins with an artifically low production from the mfg, that builds demand. It's a marketing move to create exclusivity, but I do not think it is healthy for this hobby.
On the other side of the equation, for new buyers into the hobby, people selling poorly shopped or repaired games to new pinball buyers at high prices really drives me crazy. I want new people to be excited about this hobby, and enjoy their machine.. but when people are fooled into overpaying for something they will be lucky to get 50% of their money back on when they decide pinball is no good because of their sucky machine.. I also do not think that is good for the hobby.
So yeah.. pingreed.. what can you do? Perhaps we need to start our own regional guilds to better control the market and break kneecaps? I'm in!