Well, I haven't seen it in the two tiny east Asian markets in my area. I definitely know that it's not in one of them, which has hardly any fresh food (they have mostly packaged stuff), but next time I'm at the better one I'll ask them to make sure. There's also an Indian market that I might check out some day.
I've noticed that most Americans who talk about durian a lot live in California, Arizona and other areas in the southwest. There's apparently a lot more of it in that region than here. When I ask people about it here they don't even know what I'm talking about. Even a friend of mine from Jamaica didn't know what it was, and I believe it does grow there, though perhaps it's not widely eaten there.
The way people rave about it endlessly on the Internet and given my difficulties when eating too much fruit, I'm a tad concerned that I might become "hooked" on it (for lack of a better term), but seeing as it's hard to come by, maybe there won't be enough temptation for that to be a problem, and I do tend to have pretty decent discipline. One thing I like about berries is that it's easy to take and eat small portions and control how much I eat, since they're so tiny.
I've been keeping my eye out for durians for many months now. The minute I spot one, I'll report it.