It seems nearly every pinball machine on ebay is 'rare' these days. Or at least 'highly collectable'.
The ones that worry me are the ones that say 'rare, only 300 made' and are missing ramps, toys or backglasses. What chance woud there be to restore any of these?

I think this is a huge problem that eBay cannot possible police. There are still honest sellers on eBay - mostly private sales with poor pictures and lack detailed descriptions. These guys know nothing about the game, and sell it because no one plays them any more.

The "rare" and "collectible" tag is used too often, and it is used to mislead the buying public. Another trend is assertion that missing or defective parts don't affect gameplay. My favorite is "Display is missing a couple of lines but it does not effect gameplay". Why not remove the display completely - that also does not "affect gameplay". It is a joke !

The rare games missing parts are a huge risk. I bought a project Flight 2000 only after ensuring the playfield was going to reproduced and I could buy the VERY rare VS-100 Vocalizer board. I have a Freefall with a poor playfield, but I took the risk. Price reflected the condition of the machine.