Wiktionary
dime a dozen
a. (context US idiomatic English) So common as to be practically worthless.
Usage examples of "dime a dozen".
If they brought in wrappers from around town, I paid a dime a dozen and threw in a cone.
In Dahl, visionaries were a dime a dozen-street-corner crazies, out of work, out of the grind, most driven insane by their work in the heatsinks.