Pinball is entertainment. A distraction from all of lifes other issues and problems. Everyone is willing to spend different amounts of $$$ on entertainment depending on financial situation and desire. For example I'd spend $5K on a pinball machine, but not on a Super Bowl ticket. I value the replay value more than the one-time experience. Other people would be the reverse of that thought process.
$5k on a pinball machine would be my max, even if it was a "dream theme". I would not buy a NIB from Stern because of the price and quality issues that are ramapant at the high price point. I say only Stern because JJP, Skit-B and Heighway have yet to officially release anything yet. I would not buy from them just the same if they have the same qualiy issues at their price point.
As previous posters have mentioned, the only way price goes down is if demand goes down. With the rising popularity in pinball, I do not see this trend stopping anytime soon. Unfortunately this high price point will make it harder for ops to recoup expenses and turn a profit on NIB games.
Also I personally would rather have multiple older SS/DMD titles than a >$5k NIB.