In the early 80s we had an electronics factory a few miles away from home. A friend and I used to cycle there in the summer evenings and weekends and avoid the security watchmen and raid the rubbish skip. Amongst all the general detritus we'd find PCBs and discarded, fully functional components including relays, LEDs and seven-segment displays. We briefly ran a small business at school selling some of our haul to equally nerdy, but richer kids - until the other kids worked out where we were getting the gear and started raiding it for themselves!