I just did it in July last year.
My guess is that pellets for $9/40lb would not be food grade.
It cost me $9/20lb bag delivered.
A large part of the cost for you is shipping to NM. The closer you are to the source, the less they cost. Current prices for LJ to MI are $15/40lbs with the popular online pellet provider.
There's currently a group buy in Port Huron - not sure how close that is to Ann Arbor. Since they are a dealer I won't disclose their name here, but I assume most folks know who I am talking about. Bentley please delete if this is inappropriate.