I get cranberry beans at the ValuMart grocery in Louisville. They're in a regular 1lb bag next to the pinto and lima beans. On sale every so often for $.49/bag. Can't remember the brand but it's the same as their other beans.
Looks like Bob's Red Mill brand packs cranberry beans, too.
Maybe southerners get better bean deals and variety?
Of course it'd be more interesting to grow one's own if there's room in the yard.