I usually just clip the wires as close as I can get to the base and sell the supply as shred. I haven't found a yard around that takes them as anything else. There are some forum members that will buy them clipped if they within driving range.

When I first started scrapping I opened all my power supplies and got the boards and sinks...I learned real quick that it is a time consuming / low reward project. Not to mention all the dust in there about killed my allergies....

Cheers,
Tom