There were/are a couple of aerospace surplus shops in the area. Apex and Norton are the ones I'm familiar with. The supply comes from the SoCal aerospace industrial base and a lot of the demand is indeed for movie props. It's a fortuitous pairing - the prop rental business seems to be keeping them going to some extent whereas a lot of industrial surplus businesses in other parts of the country seem to be struggling these days.
Isn't that the location of the soundstage where they filmed the Apollo landings? I would think it would be rich in appropriate resources. Flags and golf balls and stuff.
Some interesting junk and scrap shops in the area. Spent a few weekend afternoons puttering around looking at random stuff.