When you buy oats by the 2.5 kg bag up here the cost goes down to about $2.25 per kg vs $3.50 per kg.
Anyhow, safe to say oatmeal is about $1.50 a pound up here, and I would hope grits might be about the same.
Great thing for hikers is that dry food can be quite cheap because it is cheaper to store and to ship.
Don't be afraid to buy in bulk sizes, like 1-2 pound bags. You can still get variety by mixing in stuff.