I know loads and loads and loads of people with old computers, including Macs. The iBook Clamshell I bought was HARDLY ever used and I snagged it for $50 and found a cheap airport card. All the other G3s were just sitting around on desks too. The G5 I just got was a school machine only used for Photoshop and Final Cut Pro.
And actually, today we just got another Toshiba that was just sitting around. Put a new hard drive and installed Windows 7, works great!
Hopefully someone leaves a G4 Mac behind one day. That's how we got the 180c in 1995 (when it was still worth about $3,000). We even gave that to a friend who used it in college and brought it back to us in the same great shape.
I think I posted the story here once, but a few years ago we found a G4 Cube in the dumpster. We think someone stole it and was looking for a place to hide it. It had water everywhere. We brought it inside, they cleaned it up, and it got sold for a couple $200-300. We should have just kept it ourselves LOL, but it was on the school's property so it could have been someone's.