Salvage is very expensive and risky: There's nothing like the high-speed and reliable PCB assembly process for dissasembling PCBs, only manual processes, and even with skilled workers there's some risk of damaging the chips, if they aren't already damaged when you got them. And there's definitely no economic way to test the chips to ensure they meet spec. You can do it in a pinch for very high value low volume products; for a thousand or more consumer devices, no chance.