ten-a-penny UK version
A kind of thing or person that's cheap, or which you can find easily and in large groups.
dime a dozen US version
something so common that its value is little or nothing.
„He was incredibly unimpressive. Short, for one thing, barely five feet tall, narrow shouldered, significantly underweight, hollow-cheeked. He had reddish-brown hair cut unfashionably close, possibly against a hint of curls. His worn suit of faded black was obviously cheap and didn’t fit terribly well; bizarrely, he wore cheap cotton gloves. He looked like a clerk, the ten-a-penny kind who drudged in every counting house, except that he had tawny-gold eyes that were vividly glowing in his pale rigid face, and they were staring at Crane with something that looked extraordinarily like hate.”