For 737 BBJ you can find some in Europe, as previously stated. Global Jet performs operations on BBJ`s mainly for russians, with base in Moscow.
About PRIVAJET, I`ve heard rumors that there are crews from French XL Airways 737`s, and they are happy to take people from there (correct me if I`am wrong).
787 BBJ in Europe? I think it`s impossible right now
Greets!