Wiktionary
a. (context idiomatic British English) very common; cheap
Wikipedia
Two a Penny is a British film released in 1968, featuring singer Cliff Richard. The film was directed by James F. Collier and produced by Frank R. Jacobson for Billy Graham's film distribution and production company World Wide Pictures. The original story and screenplay was written by Stella Linden.
The cast included Ann Holloway, Dora Bryan, Avril Angers, Geoffrey Bayldon, Peter Barkworth, Mona Washbourne, Earl Cameron, Charles Lloyd-Pack, and Billy Graham himself, filmed at his "London Crusade" in 1967.
Usage examples of "two a penny".
Gunfire erupted from a window high above them, but it was only a bass player getting shot for playing the wrong riff three times in a row, and bass players are two a penny in Han Dold City.
Even in these days when kings are two a penny, and there is a never-ending procession of Napoleons and Nelsons to the Guildhall to receive swords and freedoms and honorary degrees, the arrival of a Shah of Persia stirs the imagination of the man in the street.
Deans and professors were two a penny: I never did discover how so many people had been bullied into coming.
When he used that word, no one would mistake him for the skipper of a spaceship--and spaceship captains were, of course, two a penny.