Salvaging Junk Equipment

When I'm not fixing someone else's equipment I'm fixing used stuff to sell to someone who needs one but cant afford a new one. I wanna know from you guys is when junking a piece of equipment cause it not worth fixing what kinda stuff should I keep from mowers, weedeaters,chainsaws, riding mowers, etc.

Right now I just keep all 4 cycle engines unless it too old then I just carbs and junk the rest. On 2cycle I been just keeping the carb too. On riding mowers and walk behinds I usually keep wiring harnesses,throttle cables, blade control cables, self propelled drive units, handle bars, headlight len, seats, wheels, transmission, and whole engine. Someone told I should be keeping the coils and recoil/rewind starters off all the 2 and 4 cycle engines but I don't.