Well, at first, yes, there's some money outlay. But once you have a good PV that you enjoy using, your only expenditures are for juice (which you can make yourself if you want to go really inexpensive, or you can buy for reasonable costs), cartos, and occasionally a new battery. Now, compare that to the common pack-a-day smoker, who (in my area) is spending at least $5 a pack (and in some states as high as $10 a pack). At $5 a pack, that's $35 a week, or $140 a month, or $1680 a year... and unless you're buying every mod in sight and every juice you can find, it's pretty unlikely you'll get up to $1680 a year every single year.
For me, it's slightly more expensive to vape than to smoke, as I rolled my own cigs, which ended up costing me about $2 a pack (and I was a 1.5 pack a day smoker, so I was still spending less on cigs than I would on a meal at McDonalds -- not that that's any safer than smoking!). But you know, the health benefits of kicking the cigs make it worthwhile, and as I plan on eventually making my own juice, the cost of vaping will end up dropping below even that $2 a pack cost.
Anyhow. I went majorly tangential here, so I'll shut up.