What is a product or service that costs pretty much the same price nowadays that it used to cost when you were a child? ~

Cigarette butts are still free. If you are broke and can't afford smokes it is still legal to pick up butts and use the tobacco to roll your own free cigarettes. 

I can't remember buying anything as a child. If I could move it up a bit to when I was a young sailor and take into account inflation, my low salary then and my 15 times that now some things are actually cheaper. Gasoline is an example. (We have the lowest gas prices in the country.)

Twenty bucks will still get you a nice hum job in the ghettos of Phoenix.