Some of the cheapest copies (4)
I believe the answer is:
apes
'copies' is the definition.
('ape' can be a synonym of 'copy')
'some of the cheapest' is the wordplay.
'some of' indicates the answer is hidden within the clue.
'APES' is hidden in the letters of 'cheapest'.
(Other definitions for apes that I've seen before include "Peas (anag)" , "Mimics like primates" , "Copies the primates?" , "Species of primate" , "Parrots" .)