I bought lockers full of Computers before, you just have to break it all down and scrap them..
1) Computer AC cords, Patch Cables, etc (Is scrapped as Insulated Wire) - I was getting a $1 a lb when I scrapped mine, I think the prices are higher now.
2) The computers casing is just Steel Scrap (You'll need a lot of it to make any type of money, I had 1500 lbs of it the last server locker I did) which is around $180
3) Take out the motherboards and you can sell those by lbs on ebay (People pay about $10 a lb for it) they scrap them for the gold content.
4) Take off all the aluminum heat sinks on the mother board, put that in the aluminum scrap pile.
5) Remove the processors, sell them by the lb on ebay.. (They are scrapped for gold content)
6) Remove all the memory, sell them by the lb on ebay. (Gold Content)
7) Remove all the cards in the slot and sell those by the lb on ebay (gold content)
8 ) Dis-mantle all the hard drives (Aluminum reader, the Platinum Platters, the Magnets) The bottom of the drive is aluminum and the top is stainless steel.. Separate it and sell the magnets and platters on ebay by the lbs.
9) Take out the power supplies, cut the wires into the insulated wire pile, then put the power supply in a separate pile, you'll get like .30 a lb at a scrap yard for it.
10) Any big power supply units with batteries (you will get paid at the scrap yard for the used batteries in it)
So moral of the story, if there is like 50 computers in a locker you got about 4k in scrap in it..
If their is like 3-5 computers, it's not worth the effort.
You can also scrap the computers whole to the yard, but you'll get way less money for it.