You're liable to fall into one of two camps - either you will find vaping to be up to 1/5th the cost of smoking or it will become a hobby for you and, as such, will represent an ongoing investment that's probably going to cost more than smoking.
To get started, you should be able to get a good starter kit for <$100 (the Kanger EVOD kit is one I recommend). After that, it's all about juice and coil units (or cartos). That is, unless (like most of us) you begin to yearn for more toys, and then............
That's why it's good to be here, there's a "guardian" so you won't overspend. Be content on what we have, and learn more DIYs... By the way spend S$100 on my eGo-Ts + Hangsens when I started. Loving it since day 1.