Sources for cheap/free electronics for students?
Maybe not what you are referring to, but salvaging components is fantastic and free, and I source most of my components from garbage people throw out.

A CRT has good high voltage components, a printer is good for the motors and rods if you want to make a CNC'ish thing, and flat screen tv's have good backlight stuff in them.

If you find old computers then you can get the memory chips out, saving you a good five bucks or so per RAM chip.

And all you need to do this is a soldering iron, a good sponge, good light, and a lot of time. Best would be to use a paint stripping gun or just stick it in an oven to get the parts to pop out. (Careful about the capacitors and other plastic items) Also, you can consider it as being green, since you are preventing land fills from getting filled with harmful materials from all these electronics. Lastly, you can learn a huge amount about electronics very quickly this way because you see exactly how it is implemented in a a working product.