Around that time there were all sorts of cheap plastic alternatives
to matchbox and dinky etc.
I have vague memories of plastic vehicles, perhaps half the size
of a standard matchbox toy.
Also consider breakfast cerials of that era
as a source of 'disposable' plastic minatures.
Don't know how well documented these are on the net,
but I definitely collected Thunderbirds toys from one popular brand
of early 60's cerial.