I was told from a guy that does it for a living about a year ago when I asked the same thing, and his answer was "your not looking hard enough". Perhaps that's true, but I don't have 24 hours a day to track down the same junk that your describing. My latest "raid" just happened this past January and it was two 10x24 storage lockers fully of pinballs, jukeboxes, antique radio stuff, one video game and tons of parts, playfields and backglass........
It night not look like much from these two pictures but trust me, a lot of stuff and I do mean ALOT of stuff.
John