I’ll never tell

There's your problem right there. Don't use "dealers" or "websites".

Cheapest way to find machines in this order:

Friends through word of mouth - a lot of times these machines are free
Tournaments (pinball friends)
League events (pinball friends)
Pinball Shows

Storage unit sell offs
Estate sales
Live local auctions in person
LOCAL online classifieds
Pinside

The closer you stay to the top of the list, the cheaper the machines will tend to be. Likewise, the lower you go on the list, the more machines there are but the prices tend to be higher.

It also matters tremendously if you are able to work on them yourself. A considerable discount can be had if you are able to quickly diagnose and repair machines. You also have to try the different zones out and see where you are more comfortable. All of these take time and your time is worth something as well.

The truth is if you truly love playing pinball, the machines end up finding you!

I have always found mine locally, sometimes via friends that know
I collect pins and at shows. Usually buy older fixer-upper games
not the newer high dollar games. I will NEVER pay ebay or internet
prices for pins.
Steve

Poll fail. I buy anywhere there is a project I see I like. So...all the above.