I was "alive" in 1957, but I don't remember much, if
anything about the ammo prices back then. Why would I? I mean, I didn't even get my first "real" gun (a Model 55 Winchester) until my 10th birthday in
1958!
I'm not sure, but I think Winchester 22LR ammo was .79 (a box of 50) in my mom and dad's country store/gas station in the early '60s. On the other hand, $150 in gross sales was a very,
very good day in the early to mid '60s in mom and dad's store, and less than 10% of that was profit. That's why Dad took a $1.65 an hour job as a boiler operator in a potato processing plant, and Mom ran the store for 11 hours a day, 6 days a week. So, taken in perspective, .79 for a 50 round box of 22LR ammo wasn't all that cheap.
BTW, before I started working in the orchards in my early teens, I pumped a lot of 31.9 cent a gallon gas at Mom and Dad's country store/gas station. There was no self-serve back then, and I washed windshields and checked oil (and sometimes tire pressures) too. And usually, "five dollars-worth" was almost a "fill-up." Soon, "five-dollars-worth" will be less than a gallon.