If you are into electronics and designing your own circuits, check out this handy tip for harvesting nearly-free components from old printed circuit boards (PCBs).
You can purchase components such as resistors, capacitors, micro-controllers and the like for relatively little, but why not recover them from old unused components for free?
With a heat gun and some time, you can de-solder the compoents from a PCB. After the melting temperature of the solder is reached, the components will come off with ease. Just make sure you use proper venting and protection from the harmful gasses that can come off from this activity.