At a low cost (2,3,5)
I believe the answer is:
on the cheap
'at a low cost' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for on the cheap that I've seen before include "At a low cost" , "Inexpensively (sl.)" , "with minimal cost" , "(Done) inexpensively" , "By cutting a corner (on expense)" .)