The pricing on the actual pinball machines themselves to purchase has been covered in other threads.
Think about it, if you have a working machine that is constantly generating income you DON'T WANT TO SELL IT.
For every machine they sell they have to go through the trouble of finding a replacement, refurbishing it e.t.c. and for what? Just so it can earn the same as the machine they just sold for a "good deal" to somebody?
It's in their best interest to price the games high because they don't want to sell them.
(And believe it or not, they DO end up selling games for those prices, in which case it's worth the trouble to find/refurbish/setup a replacement game)