Yeah, what they said. The costs of vaping largely depend on how and what level you get into it. The most basic level (the little disposable ecigs) may seem a fairly comparable (to cigarettes) way to enter vaping, but it will some become pricey to continue and won't provide as good of an overall experience for most as well.
Getting into the next level of tools like the various eGo devices, attys, cartos, tanks and small bottles of ejuice cost a bit to get setup, but immediately with produce some significant savings for you over the first 30 days or so to say nothing of a far more enjoyable experience.
Beyond that level, you can get into APVs, rebuildable tanks and cartos, and DIY ejuices. Again, you'll layout a bit more money for the supplies initially, but the cost savings from these setups can result in an equivalent of probably $0.30 USD per pack of cigs or less to say nothing of an experience comparable to Smoking Heaven when compared to premade cigarettes.
So in a nutshell, a good vaping setup should help you save tons of money over smoking premades. That is to say, you will save lots of dough as long as you don't go bat..... crazy over gear and juice, and develop some acquisition disorder like some do whereby you end up spending WAY MORE money than you did on cigs just because you can't stop buying stuff.