I doubt you'll get one here in the UK any more, unless there's some old stock left sitting in a store room somewhere. Part of the deal when Phoenix NW sold the Belstaff name back in 2005 was that there should be no old stock left on sale after July (?) of that year.
However, the jacket is still available from British Motorcycle Gear in the USA and the even better news is that a revised version of the Adventure pants is soon to follow. The downside is obviously that the exchange rate is nothing like as good now as it was this time last year.
i brought one from somebody on this site a while ago, great jacket, for the summer ,and the waterproof inner is preaty good .. have you tied the wanted section