Around here, walmart sells it, although not always much far into the fall.
If you're gonna have to drive for it, I'd go ahead and try to get something that lasted longer, though. For example, if you're not far from an Academy Sports, (which I know they have in Oklahoma City and Tulsa, and a couple other OK cities), get some B&B oak lump. I pretty much use Stubbs natural briquettes for all my long low-n-slow cooks, but the B&B lump has worked well for me.