I asked this same question a year or so ago, after seeing live langoustines in Toronto. Apparently they are perishable (and expensive), as I recall someone said that New Deal once carried them but stopped for this reason.
I did find some suppliers and so you could order them yourself, here's one:
Unlikely. They are highly perishable and very difficult to transport that its probably too pricey to bother for most fishmongers. I'd love to know too, so please share if you find any.