My suggestion to you is to check to see if there are any state or military surplus locations near where you are. I work for one of these, and to be honest with you we send all of our old electronics off to be melted down and have the precious metals recovered. A gaylord (4X4X4 box pallet basically) full of motherboards/addon cards will fetch between 1200 and 1500 dollars this way, and it's just more practical for us to send the material off and make money this way than have it take up warehouse space. We break the sorting down into pallets of Printers/tape/scanners , computer towers, monitors, and scrap wire. We have an occasional private buyer that will come in and purchase a pallet of printers for robotics or home brew electronics. We have also sold pallets of components to schools so that their classes can work with the items as well.
The majority of surplus locations I have talked to do much the same thing as this. Processors are very difficult to find, as the old 386/486 are very heavy with precious metals. I think it's near $30 a pound right now. The newer processors don't have nearly as much, but do still fetch a fair amount. As far as operation, a lot of state and federal surplus locations only sell to the general public a few times a year. Our location has a monthly sale to the public. The rest of the year is reserved for government agencies and non profits.
One thing you might have problems with is that a lot of these locations are becoming more and more protective over data security. You'd probably be hard pressed to find a location that will sell you a computer with hard drives in it or anything which can hold possible confidential data. But they should be able to just pull those items and sell you the rest if you ask.
Anyways, apologies for the long response, but i really believe that these places are a massive source of components that most people don't know about. I've picked up fluke multimeters for $5 and tek scopes for as little as $40. They're older, but work fine for everything I use them for. Aside from electronics you can find great sources of scrap plastic sheeting and often times aluminum and sheet metal. I picked up a 4X4 sheet of lexan for $1.You can get just about anything at these locations, and if you know someone who works there you've probably just found a goldmine as far as parts go.
So if you curious, do a google search for surplus locations in your area. Most likely all of your colleges will have one, and if you live near your state capital there is a good chance that a federal surplus location will be near you as well. Happy Building