I've been vaping for 2 years 3 months. I just did a calculation of what I would have spent on cigarettes vs what I spent on vaping and here are the numbers:
Money spent on ecigs to include purchase of batteries, eliquids, and coils, and set ups for that period of time: $4,418.80
Money I would have spent on cigarettes based on 1 carton of cigarettes per week which cost me $60/carton for that period of time: $7,269.60
Overall savings so far: $2,850.80
If you have to buy everything you see advertised, there is no end as to how much more money you'll spend. It's like anything else, when you see something new and shiny ask yourself "Do I really need this based on what I've tried so far? or, does the equipment I have keep me off of cigarettes?
In the beginning you will spend money up front. The batteries and charger you just bough will last you quite a while, my batteries have lasted me this long so it's not a monthly expense. Set up a budget and try to keep to it as much as possible. It's just managing your money in the end.