Movie prop makers used to pay good money for stuff like that - like maybe $5 each. Of course, that was before Airsoft.
Prop-makers would make three or four versions of "custom" movie rifles, make molds and castings, then junk the originals. No BATFE regs, no live firearm hazards, minimal security concerns.
I used to supply some of that junk. Some came from police dump sites, some from scrapyards. When you pay a maximum of $32 per ton for this kind of junk, $5 per item for chunks like this is OK money.
Hey, it kept me in school!