I always like to search for local auctions on ebay.
To date I have gotten.
2 Monitors.
6 or 7 computers
1 Defender coin door.
Sprint One (minty, complete, boardset problem). $50
Force II pinball (was NW, now it sort of works, but not correctly). $150
Solitaire Challenge (MINT, had boardset problem, then later the monitor blew up, I used it for Mame). $50ish.
Also picked up a solid 9/10 dedicated Super Strike for a buddy for only $150.