I've bought non-working pinball machines from Facebook Marketplace or Craigslist for great prices and brought them back to life. They cover a range of the pinball spectrum from electromechanical games from the 1970s through 1990s games with dot matrix displays. I fix these up, play them until I get bored of them, then sell them to make room for future projects or trade them for something new-to-me.
Separately from that, I've bought, sold, and traded to end up with a set of games that I enjoy playing. There are a couple of modern Stern games in the mix along with some mid-90s Bally/Williams games.