Please check out Common Sense With Money's post on cheapie dog food here.
As a somewhat late heads-up, the most recent issue of All You magazine (March 26, with teal blue cover) has the following Pedigree dog coupons, $7 total savings:
$1/Marrobone or Jumbone
$2/Pedigree Dry Food for Dogs, any one bag
B1G1 Free, Pedigree Canned Food for Dogs (up to $1.09 value)