I'm sorry, but I think that your theory makes no sense what so ever. Maybe 3-4 years ago Stern was the only show in town. Now, there are at least 5 companies making pinball machines, and that number will most likely increase. The technology is getting better by the day, and the market for pinball machines, and associated products is growing by the day as well. With a growing market and the number of existing and very collectable machines decreasing daily; the price has nowhere to go but up.
Although highly unlikely, due to the growing number of new machine buyers; the price for new games could possibly decrease slightly or stay the same, but the older machines and machines that are no longer being produced have a much better chance of going up in value.
I strongly believe that games like Wizard of OZ will see dramatic increases in value once they are no longer being produced.
The hobby is in an upswing. The market is growing and there is absolutely no reason for it not to continue to grow at an even more accelerated rate than it has been. Pinball bars and arcades are popping up everywhere. Tournaments and leagues are getting more and more popular. Pinball shows are growing in size and becoming more popular year after year .
You sound like someone that just wants to pay less for his games. It is just not going to happen any time soon, and their is a much better chance that the value of the top 100 games or so increase in value substantially over the next 10 years than there is for them to decrease in value at all.
Unlike the stock market, which is controlled and fixed by the hedge fund managers and the extremely wealthy .... The pinball marketplace is a great supply and demand example, and all indicators are pointing upwards.
Manny