Quoted from Bublehead:

The biggest problem with the "New Popularity" of pinball is the massive influx of noobs who have money and no time... so NIB and HUO is as popular as ever, and these noobs tend to drive prices into the stratosphere... So now the old phucks like myself sit back and watch the bubble get bigger and bigger, wondering what is going to be the event that triggers the " massive sell offs" that I expect will eventually come. Whether that is a time based trigger, or a economic based one, or a "its broke and nobody knows how to fix it" scenario, pinball popularity will eventually crash again. Either way, who on this next big wave of price diving sell offs is going to snatch up all these machines and sit on them until pinball once agian finds its luster? You used to be able to find barn fulls of old pinball machines, rusted, rotted, and roached into oblivion... will the trend this next time around be cobweb filled game rooms of toppered machines? Time will tell.