I was a lifelong and heavy smoker, I went on to e-cigs, the first couple of weeks it was difficult, comparable to drinking a weak shandy rather than a full strength beer, but then e-cigs became my norm and after 6 months of those I gave up smoking totally and I've been some three years without.
As I recall a bottle of the e-liquid was about the same price as a packet of fags, well one bottle of e-liquid was lasting me around two months!
No e-smoking on flights is one of those rules that is difficult, if not impossible, to enforce. It is not smoking as there is no fire and no smoke, merely a water vapour and they have yet to fit water vapour detectors in aircraft loos and even sitting in one's seat one can cup the cig in one's hand, take a puff, swallow the vapour and nobody around will be any the wiser.