I think it is fair to say everything has gone up in price this last 3 years.
The good thing though, is because there have been so many machines imported, it is easier now to get ya hands on most titles as people sooner or later get bored with a title and want to move it on to get something else. Even so, some titles like Indiana Jones, Next Gen and Twilight Zone still hold their values well, as does stuff like Monster Bash, Atack from Mars, and Medi-evil Madness etc etc. Ya just have to find the right seller at the right time to snag a bargain.
Alot of people list ebay auctions very close to Xmas with dreadful results. Every year I pick up machines for half price cause an auction is run too close to Xmas, lets see what gets listed too close to Xmas this year with no bidders. lol