Pinflation is driven by two factors:

1. Growing number of middle-aged folks with expendable funds discovering pinball as a hobby.
2. Regularily increasing NIB prices well above real inflation.

So long as Stern can keep increasing the prices for their games every year they will keep dragging the prices of all games upward with them. It's basically a bubble, and will continue until the market demand for every expensive toys is truly saturated. This will occur once those of us who knew pinball back in the day (came of age in the 70s, 80s, and early 90s) grow too old to move 250lbs boxes around, or too broke to pay for them.

I'm not completely discounting the Millennials interest in pinball here, but there numbers are too low to sustain the market on their own without a large amount of contraction, hence, the bubble pops.

Make no mistake though, once "peak-pinball" occurs, it's going to be a bloodbath, with way more games available than interest in buying and prices collapsing as a result. Maybe another 20 years, maybe 20 months, who knows.

We all have to keep in mind that it's basically the same 2000 folks regularly buying and selling these high end pins.

So when a shiny new GnR or whatever hits the market it shakes loose a lot of existing games out of collections to make room/$. All these games flooding the market at once tends to reduce prices, temporarily. Other times when there is no "gotta-have-it" new game hitting the market collections tighten up and prices increase.

Right now between GnR and AIQ lots of new games are inbound forcing older games to the market. It will pass.