As kids, we used to have a salvage yard that would let you remove the parts for yourself and they would charge less. Since we had our toolbox, we put as much stuff as we could carry and just put oily rags on top of it. If it was a bigger part, we would put it by the fence and come back at night. We always brought treats for the dogs during the day so they would recognize us. It's been 40 years since I last did it, so can't speak to security these days.