There were a lot of such things in small ads in the back of "men's magazines" like True and Argosy, and in gunzines even though you could then buy a real pistol mail-order.
There is an article in an old Gun Digest about movie guns. Most were real guns bought cheap on the used gun market and accumulated ever since the studios opened. At one time, SAAs were cheap.
I recall an article about Bonanza describing the rubber guns they carried when shooting was not scripted. Lighter to carry and not as hard to roll on when the hero elected to duke it out with a crook instead of simply shooting him.