I got a gutted Doctor Who for $200 on craigslist. LED tvs cost nothing these days, paid $250 for a 40" insignia for my playfield, fit like a glove without decasing. Got a 29" with a small scratch on the screen for $90 on ebay, fit perfect for my backglass. And for my DMD I used a old 19" Dell VGA monitor from the basement. The computer I had laying around and put a $100 video card into it, runs like butter.
Few other buttons and parts, I built mine for less than $800.

The games are a great way to introduce you into rule sets, and what real pinballs you might want to buy, its certainly no substitute. But I would have never bought a real one if I hadn't built my virtual one first to get the bug.