I made a lot of mistakes in the beginning, and then there was the learning curve of finding my personal preferences. I've probably spent around a thousand dollars by now, though I try not to tell that to the people wanting to try it out. When someone asks me how much it costs, I usually show them the Ego Twist and a vivi nova, maybe a cig-alike. I don't show them my new Provari, that's for sure. If someone had handed me a Provari to try out as my first e-cig experience, I'd still be smoking traditional cigarettes. It's very large, very heavy, and very expensive. I'm still getting used to the size (obligatory "That's what she said!"), but the performance is outstanding.
As far as general e-cig expenses goes, it can save you a lot of money, or if you constantly upgrade your equipment (like I can't seem to stop doing), it can be an expensive hobby.
ETA:
I don't think I bought much that I didn't use. I probably spent a lot more than I should have on the clearos and the CE3s, and put up with a lot of leaking without realizing there were better options (vivi novas have been stellar and I use them exclusively now). My purchases were gradual upgrades, but I don't regret starting out small, at least not much. I was able to give away a lot of my beginning set-ups to curious smokers, even if they didn't end up switching. I don't feel it was a waste in that regard.
I still have two automatic 78mm Volts that are finicky and a PCC that never get used, as well as 10 CE3s filled with various flavors that have a tendency to leak and have firing issues due to bad connections. I'd feel bad giving most of these away to beginners in case the various problems turn them away from e-cigs altogether. The PCC is the only thing I'd be willing to donate, since it's reliable, but it's an 808 connection and would probably only work with Smokeless Image Volts. I also struggle with agoraphobia which makes visiting the post-office difficult.
but I love them all and would buy most of them again if I had to do it all over again. 
