None of the Wal-Marts in my area (NM) seem to stock it (alas!). Just under $20/box seems to be as good as it gets in the local shops, although Cheaper Than Dirt lists it for $15.49 a box (with some obscene amount of shipping to be added later) and Cabela's has a couple of Remington's light loads for $16.49.
Cor-Bon certainly seems to be a tad pricy. Perhaps they gold-plate their shells.
cheers,
erich