In what country was this? And when?
We shot BRICKS of .22LR and BOXES of 12GA/20GA/.410 when I was growing up. And it was cheap and easy to get. This was in the South and Midwest of USA, in the 70's - 80's.
Go back another 30 years. I bought 22s by the round(Oklahoma). Used a rifle that my Grandmother bought in Virginia for a quarter after the Civil War.
Before 1968 when money was tight and backed by silver, a hardware store clerk could break open a box of 20 and sell 4 or 5 rounds. .22s were still sold by the box, .45 cents for a box of 50, no questions asked.
Then Bobby Kennedy was murdered and the USA went into an anti-gun hysteria. The 1968 Gun Control Law was passed, Army surplus guns disappeared, ammo could be only sold by the whole box AND your name written in a book, you could NOT buy guns out of state.
Reagan changed the ammo requirements and rifles can now be bought out of state, but not handguns. We lost the “privilege” of owning new full auto firearms as a result.
Now paper money backed by government promises flood the nation and some surplus ammo is “cheap”.