Some have posted about having trouble finding Duke's outside the South. I happened to go into a Family Dollar store the other day with a friend who shops there- to my surprise, it isn't a "dollar store" at all, more of a small general market with household items and a food aisle. Anyhow, out of the corner of my eye I saw a familar-looking yellow and black label and yes. it was Duke's mayo. A bit further down, there was Wolf chili on the shelf too. Also a couple of other guilty pleasures I hadn't seen around here in the Northeast, like Sweet Sue chicken & dumplings.
I checked online and the chain has thousands of branches nationwide. So for those who've been missing the taste of Duke's, it might be worth seeing if there's one near you, too.