Can't tell you just where to buy them, & I don't have enough to share right now, but their official name is Lycoris squamigera, also known as surprise/magic/resurrection/naked ladies. I prefer the last name myself, kinda fun to tell people I have naked ladies in my yard. You might find someone locally who has a patch of them, they can be found at old farmhouses in Ky & TN I know, I remember them when I was a kid. I don't see them locally for sale though, but most catalogs have them. Or watch the exchanges, they are offered pretty regularly. This site describes them: http://davesgarden.com/pf/go/517/
Mine aren't doing to well, had them a couple of years & have had to move them twice, they don't like being moved that much. They are in bloom now, but if I hadn't moved them they would have been much prettier.