An egg is only worth eating if it provides your body with
nutrition
If your only reason for eating is to stave off hunger then by all means eat the cheap ones, where the hens have fed off junk.
If you care about
nourishing your body, it matters what that hen ate.
What that hen ate can affect whether the egg is worth cooking and eating
For detailed facts see here-
http://ressources.ciheam.org/om/pdf/c37/99600038.pdf