No kidding. 50 cal shells, de-primed and cleaned go for something like a dollar each. Talking with some old-timers, still a few around: although the Japanese never got to Fairbanks, they were ready for them; it would have been a fight.
I was ten years old and would find them laying around. The temptation to strike them was, well, tempting. I'm glad I was smart enough not to. Never accured to me to sell them- I would collect them and attached them to each other forming belts. Who knows how close I came to getting hurt!