When was about three, I remember having a lot of battered old toy cars which for some reason were kept in a vinyl shopping bag. No two of them were to scale, but that didn't worry me too much when I was three. They all got rolled along the same carpet with the same 'brumm brumm' noise.
In time the whole bag got passed on to Neil Brison, who no doubt battered them up considerably more, but when I was old enough to have pocket money I started up a fresh collection - this time of nice shiny new Matchbox cars.
Each model of Matchbox car was numbered, so if you had "No 74 - Ford Capri" that meant you had at least another 73 to collect. Because if you didn't, someone else would.
They all cost 24p, but the best ones had boots, bonnets or doors that opened, so you had to get those ones first.
One of my first Matchbox cars got eaten by a zebra in Edinburgh. I took better care of them after that.